manhattan模考遇到的一道题，求解释

		twice as much as 1981
		twice as many as 1981
		double the figure for 1981
		double what it was in 1981
		a number double that of 1981’s

正确答案是C double the figure for 1981

不明白的是，198，113 in 2003能和the figure for 1981平行吗？

官方解释：In the original sentence, “much” incorrectly references the quantity of female graduate students. Students are countable, so “many” is the correct term. Additionally, “as 1981” incorrectly completes the comparison, illogically comparing the number of people (the “198,113 female science and engineering graduate students”) to a year (“1981”).
(A) This choice is incorrect as it repeats the original sentence.
(B) “As 1981” incorrectly completes the comparison, illogically comparing the number of people (the “198,113 female science and engineering graduate students”) to a year (“1981”).
(C) CORRECT. “Double the figure” places the emphasis on the number of female graduate students, and correctly completes the comparison between the number of people in one year (198,133 in 2003) and the number of people in another year (the figure for 1981).
(D) “What it was” is wordy, awkward, and unclear.  The singular pronoun "it" has no clear antecedent.
(E) “Double that of 1981’s” is wordy, awkward, and unclear. The singular pronoun "that" has no clear antecedent. The possessive "1981's" is not followed by a noun to possess.