A company that manufactures storage bins for grains made a drawing of a silo. The silo has a conical base, as shown below:

FIGURE SHOWN IN PHOTO

Which of the following could be used to calculate the total volume of grains that can be stored in the silo?

A: π(6ft)2(2ft) + one over three π(10.5ft − 6ft)2(2ft)

B: π(2ft)2(6ft) + one over three π(10.5ft − 6ft)2(2ft)

C: π(6ft)2(2ft) + one over three π(2ft)2(10.5ft − 6ft)

D: π(2ft)2(6ft) + one over three π(2ft)2(10.5ft − 6ft)