A company that manufactures storage bins for grains made a drawing of a silo. The silo has a conical base, as shown below: Which of the following could be used to calculate the total volume of grains that can be stored in the silo?

A. π(8.5ft)2(2ft) + one over three π(2ft)2(13ft − 8.5ft)
B. π(2ft)2(8.5ft) + one over three π(2ft)2(13ft − 8.5ft)
C. π(8.5ft)2(2ft) + one over three π(13ft − 8.5ft)2(2ft)
D. π(2ft)2(8.5ft) + one over threeπ(13ft − 8.5ft)2(2ft)