Roy uses 1/4 cup of batter for each muffin. which list shows the amounts of batter he will use depending on the number of muffins he makes? a: 1/4} {1/5} {1/6} {1/7} {1/8}. b: 1/4,2/4,3/4,4/4,5/4.
c: 1/4,2/8,3/12,4/16,5/20. d: 1/4,2/8,4/16,6/24,8/32.

I think this is one of the reducing fractions problem:

If we look at option A.{1/4} {1/5} {1/6} {1/7} {1/8}.
Here, the reduced form of all the fractions is not equal to 1/4

If we look at option B. 1/4,2/4,3/4,4/4,5/4.
Here, the reduced form of all the fractions is not equal to 1/4

if we look at option C. 1/4,2/8,3/12,4/16,5/20. 
Here, the reduced form of all the fractions is not equal to 1/4

If we look at option D.1/4,2/8,4/16,6/24,8/32.
Here, the reduced form of all the fractions is equal to 1/4
i.e.  
1/4 = 1/4
2/8 = 1/4
4/14 = 1/4
6/24 = 1/4
5/20 = 1/4

So, the correct answer is D.