Tanks A and B are each in the shape of a right circular cylinder. The interior of tank A has a height of 8 meters and a circumference of 8 meters, and the interior of tank B has a height of 8 meters and a circumference of 10 meters. The capacity of tank A is what percent of the capacity of tank B?  Select the correct option.
A) 64 %
B) 80 %
C) 100 %
D) 120 %
E) 125 %

Rationale: "for a , r = 8 / 2 pi . its capacity = ( 4 pi ) ^ 2 * 8 = 128 pi for b , r = 10 / pi . its capacity = ( 5 pi ) ^ 2 * 8 = 200 pi a / b = 128 pi / 200 pi = 0.64 a"
Answer: A