GMAT Sentence Correction (SC) | Re: When drive-ins were at the height of their popularity in the

The comparison is about the number of drive-ins, which is a countable noun. so looking at the answer

A. there are less than one-quarter that many :less is for non-countable
B. there are fewer than one-quarter as many :fewer is correct
C. there are fewer than one-quarter of that amount:fewer is correct, but amount is for non countable
D. the number is less than one-quarter the amount :less is for non countable E. it is less than one-quarter of that amount :less is for non-countable
So answer
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