You need to buy laundry detergent and your favorite brand comes in three different sizes. size 1 costs $7 and is enough for 28 loads, size 2 costs $14.72 and is enough for 64 loads, and size 3 costs $24 and is enough for 100 loads.
pick the size that has the best deal.

a. they are all the same
b. size 1
c. size 2