In this example, using the term “depicting,” whether we include the comma in “paintings in the museum, depicting,” or eliminate it as in the original construction, introduces a participial modifier. This modifier correctly refers back to the series of paintings in the museum, but leaves the sentence without a conjugated verb. The construction “paintings in the museum, which depicted​” makes a similar mistake, as the relative clause “which depicted” also leaves the sentence without a verb in verb form. The correct answer, “paintings in the museum depicted​,” corrects this error, as the past tense verb “depicted” creates a complete sentence and agrees with the subject, “a series of paintings.”

In this example, the existing phrasing, “her having,” appears to be an attempt to construct a participial modifier referring back to “his mother,” but the inclusion of the pronouns “her” renders the choice redundant and grammatically incorrect. The choice “she had” creates an independent clause within the commas, which cannot occur grammatically inserted into the middle of a sentence. The choice “which” renders the clause within the commas a relative clause, which might seem correct, but “which” seems to convey the incorrect sense that “his mother” is an inanimate object. The choice “who had,” on the other hand, similarly introduces a relative clause which correctly signifies that “his mother” is a person, and it is accordingly the best choice.

In this example, the existing phrasing, “that flourishes,” makes the remainder of the sentence a relative clause which describes the “vibrant plant life.” However, this choice leaves the sentence without a conjugated verb, making it an ungrammatical fragment. Deleting the underlined portion makes “in unexpected places” a prepositional phrase to describe the “vibrant plant life,” but the sentence is similarly left without a conjugated verb. The choice “flourish” is problematic because of subject-verb disagreement between “vibrant plant life,” which is singular, and “flourish,” which is conjugated to agree with a plural subject. Alternatively, the choice “flourishes” provides the sentence with correctly conjugated subject-verb agreement.

In this example, the choice which includes a comma followed by “and” is incorrect because of the relationship between the two clauses. Because the first clause begins with the subordinating conjunction “because,” it introduces a subordinate clause, which should be set off by a comma when it precedes an independent clause. The inclusion of “and,” however, means that a subordinating conjunction and a coordinating conjunction are used, ungrammatically, in tandem. The choice which includes “then” and no comma is wrong on two counts, as it fails to include a comma to separate the subordinate and independent clause, and the use of “then,” which indicates causation, is redundant with the subordinating conjunction “because,” which has already signaled a causal relationship. The existing phrasing, with no conjunction and no comma, is incorrect because a comma is necessary between an independent clause and a subordinate clause which precedes it. Accordingly, the choice with the comma and no conjunction is these, as there is no redundancy in conjunctions and the comma correctly separates the two clauses.

In this example, the choice which uses a semicolon suggests that both clauses are independent. The first clause, however, cannot stand alone as a complete sentence, as it does not contain a conjugated verb. For a similar reason, the choice which uses a comma and “so” can be discarded. A comma followed by a coordinating conjunction like “so” can only separate independent clauses, and as previously discussed, the first clause is not a full sentence. The choice which uses “because,” a subordinating conjunction, is also incorrect, as it suggests that the second clause is subordinate, but the first clause is not an independent clause, and subordinate clauses cannot appear unless adjacent to independent clauses. The correct choice, then, is the existing phrasing, containing only a comma, as it correctly marks the first clause as a participial clause followed by an independent clause.

In this example, the existing phrasing is ungrammatical, as an appositive clause is followed by a relative clause. In context, “one of the pioneers of bebop style” is an appositive clause which describes who “Charlie Parker” is, and it is followed by “which,” a relative pronoun which marks the remainder of the sentence as a relative clause describing “bebop style.” This choice, however, contains no conjugated verb, making the sentence a fragment. The choice to replace the comma with a semicolon, retaining “which,” is no better, as it suggests the clauses preceding and following the semicolon are independent, which they are not. The choice with no punctuation makes the sentence after “Charlie Parker” appear to stand alone as an independent clause, but this leaves a noun set off by a comma at the beginning of the sentence, for which there is no grammatical justification. The correct choice includes only a comma, as it correctly makes “one of the pioneers of bebop style” into an appositive clause which describes Charlie Parker, while the remainder of the sentence contains a conjugated verb and a description of how he changed jazz “for decades to come.”

In this example, the existing phrasing means that everything which follows “who,” a relative pronoun, should be interpreted as part of the relative clause, as there is no other comma in the sentence to mark the end of the clause. This leaves the sentence erroneously incomplete, as the complementizer “that” suggests that something Americans have “no reason” to do will be introduced after the relative clause. In examining the other choice which doesn’t contain a comma, it appears similarly erroneous, as the relative clause continues through the end of the sentence, never revealing what it is that Americans have “no reason” to do. The choice containing “to have” seems like it might work, as the relative clause is closed with a comma, but in removing the relative clause to examine the remaining sentence, “no reason that Americans to have a hand” remains, and it becomes clear that the complementizer “that” and the infinitive construction “to have” do not function together. The final choice, with “should have,” uses the relative clause correctly, and in removing it, we are left with “no reason that Americans should have a hand,” which is entirely grammatically correct.

In this example, the choice containing “who” and “which” both suggest that the information to follow is part of a relative clause. The comma before “which” suggests that the clause is non-restrictive, while the absence of a comma before “who” suggests that the clause is restrictive. In either case, however, the sentence is left without a conjugated verb, so neither choice is the correct one. The choice “industry has testified” might seem right, as there appears to be a conjugated verb, but there is subject-verb disagreement between “experts,” which is plural, and “has,” which is singular. The existing phrasing, on the other hand, has correct subject-verb agreement, meaning the sentence contains a conjugated verb and is otherwise grammatically correct.