When drive-ins were at the height of their popularity in the late 1950’s, 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 (C)
E. it is less than one-quarter of that amount
why C? and why not D? | 
