12. According to a recent study of consumer spending on prescription medications, increases in the sales of the 50 drugs that were advertised most heavily accounts for almost half of the 520.8 billion increase in drug spending last year, the remainder of which came from sales of the 9,850 prescription medicines that companies did not advertise or advertised very little.

A、 heavily accounts for almost half of the 520.8 billion increase in drug spending last year, the remainder of which came
B、 heavily were what accounted for almost half of the 520.8 billion increase in drug spending last year; the remainder of the increase coming
C、 heavily accounted for almost half of the 520.8 billion increase in drug spending last year, the remainder of the increase coming
D、 heavily, accounting for almost half of the 520.8 billion increase in drug spending last year, while the remainder of the increase came
E、 heavily, which accounted for almost half of the 520.8 billion increase in drug spending last year, with the remainder of it coming

【正确答案】 C

【答案解析】 Grammatical Construction; Verb Form
The sentence indicates that according to research, increases in sales of the relatively small number of the most heavily advertised drugs accounted for nearly half of last year's total increase in drug spending. The sentence is flawed because of subject-verb disagreement, and an ambiguity in the referent of which.
A The singular verb form accounts fails to agree in number with the plural subject increases. What the relative pronoun which refers to is unclear; to make clear sense, it should refer to the... increase.
B The phrase were what accounted is unnecessarily wordy; the semicolon before the remainder signals that a complete clause will follow, but what follows is not a complete clause.
C Correct. The sentence is clear and grammatically correct. The subject and verb agree.
D In the resulting sentence, no main verb follows the main subject increases.
E The resulting sentence lacks a main verb for the main subject increases.
The correct answer is C.