The example sentence is run-on, as two independent clauses are connected using a comma. The best correction here would be to simply replace the comma with a semicolon or follow the comma with a conjunction. Both clauses could be their own sentences, but the writer wishes to connect them grammatically to suggest that one was caused by the other.

The sentence is a compound sentence, or one sentence that contains two complete thoughts joined together to highlight their relationship to each other. All compound sentences must be joined either by a semicolon or a comma and a conjunction. The only answer choice that appropriately does this is "She liked the finer things in life, and she always had to have nice clothes and fine food."

The sentence as written is a compound sentence, or two complete sentences joined into one sentence to show the relationship between the two thoughts. All compound sentences need to be joined by either a semicolon or a comma and a conjunction. The only answer choice that appropriately does this is "Patients were not allowed in many different parts of the clinic; they were restricted to staff only."

The sentence is a compound sentence, or two sentences that are joined into one sentence to show their relationship. The two independent clauses that form a compound sentence must be connected by either a semicolon or a comma followed by a conjunction. The only answer choice that appropriately employs either of these ways of joining two independent clauses is "The television show became an overnight success; it quickly became the network's biggest hit."

The sentence is written as a compound sentence, with two independent clauses joined together to show their relationship. All compound sentences must be joined either by a semicolon or a comma followed by a conjunction. The correct answer is the only answer choice that features the appropriate joining, "on small farms, and the use of the animals."

The sentence is a compound sentence, one that joins two independent clauses together to show their relationship. Any compound sentence needs to be joined by either a semicolon or a comma followed by a conjunction. Only "one-on-one, but he kept" properly joins the two independent clauses of the compound sentence.

The sentence is written as a compound sentence, one that joins two indpendent clauses in one sentence in order to show their relationship. A compound sentence can only be joined by either a semicolon or a comma followed by a conjunction. The only answer choice that properly joins the two clauses is "exemplary students, and she was always proud."

"What's that noise?" and "Oh, it's only the cat." are two separate sentences, not one sentence that is broken up by the phrase "asked Thelma." So, that means that a period is needed after "Thelma," and that "Oh" needs to be capitalized as the first word of a second sentence. The placement of the period after "cat" but before the double quotation marks is correct in American English, so its position does not need to be changed. Also, "Oh, it's only the cat" is a declarative statement, or at least we have no context clues that suggest it to be a question, so the answer ending the statement with a question mark is incorrect. That answer is also incorrect because the question mark falls outside of the quotation marks when it would need to be be inside of the quotation marks if the statement were a question.

The error in the sentence as it is written is that there it doesn't contain a verb. "Troubling" is actually a participle, a verbal that acts like an adjective; in the sentence given, it is describing "developments." To make a participle into a verb, one needs to introduce a form of the verb "to be" immediately before it; therefore, "In every part of the world there are troubling developments in politics" is the correct answer choice, as it is the only one that correctly inserts a verb.

The answer choice that changes "troubling" to "trouble" may look like a potentially correct answer, since "trouble" can function as a verb (as in "The questions he cannot answer trouble him"), but in this case, the verb "trouble" doesn't have a plural noun to refer to; it is followed by "developments," but "trouble" is a transitive verb—you don't just "trouble," you "trouble" something, so even if it were intended to refer to "developments," it would still be grammatically incorrect from having nothing to refer to.

The sentence is a compound one, featuring two distinct sentences, joined by a conjunction. As such, the second phrase, beginning with the underlined portion, needs to have a subject and a verb as with any sentence; therefore, "and they were able to take" is the best choice among the answers.