This sentence contains a comma where one is not necessary. Commas are generally used to separate clauses, but the word "ever" is in the same clause as "written," and they are not coordinate adjectives. The comma should be omitted. Note that no additional punctuation is necessary because prepositional phrases do not start new clauses, which is necessary for the use of any of the punctuation present in the above choices (commas, colons). The correct choice is, "the longest books ever written in history."

This sentence does not contain commas where they are necessary. The phrase "who completed the challenge faster than anyone else" is an example of a relative clause, which gives more information about its antecedent: Sharon. Any such phrase that occurs in the middle of a sentence must be introduced and completed with a comma. The correct answer choice is, "Sharon, who completed the challenge faster than anyone else, would."

This sentence contains a comma where one is not necessary. Commas should only appear before conjunctions when that conjunction joins two independent clauses. The word "bleak" is not an independent clause. The correct choice is, "was short and bleak."

This sentence misuses the comma before "and." Commas should only appear before conjunctions when the conjunction joins two independent clauses. The clause "prepared to leave for the airport" cannot be an independent clause, however, because it does not contain a subject. If a "he" were added before the word "prepared," the comma would be fine. The correct choice is, "He packed his bags and prepared."

This sentence does not use a comma where one is necessary. Commas should always come before any direct quotation that appears in the middle of a sentence. A comma should appear after the word "said." Note that one of the choices offers this, but has single quotation marks (single quotation marks should only be used when the quote appears within another existing quotation). The correct choice is, "once said, "Life isn't about finding yourself. Life is about creating yourself." "

The words "sleek" and "fast" are coordinate adjectives: adjectives that modify the same noun separately, but are not separated with a conjunction. Coordinate adjectives need to be separated with a comma. The correct answer choice is, "The sleek, fast car broke."

The words "small" and "rare" are coordinate adjectives: adjectives that modify the same noun separately, but are not separated with a conjunction. Coordinate adjectives need to be separated with a comma. The correct answer choice is, "She sought the small, rare collectible."

This sentence does not contain commas where necessary. The phrase "which led to the building" is an example of a relative clause, which gives more information about its antecedent: the path. Any such phrase that occurs in the middle of a sentence must be introduced and completed with a comma. The correct answer choice is, "path, which led to the building, was."

This sentence does not contain a comma where necessary. The words "long" and "detailed" are coordinate adjectives: adjectives that modify the same noun separately, but are not separated with a conjunction. Coordinate adjectives need to be separated with a comma. The correct answer choice is, "The boy wrote a long, detailed letter."

This sentence contains a comma where one is not necessary. The word "that" as it is used here does not require a comma before it. The word "that," while is begins a new clause, is not separated from the main clause with a comma (e.g. same happens with the word "because"). The correct choice is, "Janice decided that she would visit."