GWD和PREP一道题答案不一

viovio1989

185.    (26406-!-item-!-188;#058&001926)    (GWD-8-Q41)

When drive-ins were at the height of their popularity in the late 1950s, some 4,000 existed in the United States, but today there are less than one-quarter that many
A. there are less than one-quarter that many
B. there are fewer than one-quarter as many
C. there are fewer than one-quarter of that amount
D. the number is less than one-quarter the amount
E. it is less than one-quarter of that amount
Prep里答案是B， GWD里是C，有高人能解答一下到底是什么吗？

kikisunflower

GWD错的哈，以前有讨论帖的。

amount修饰不可数的