Answer:
Option C.

Explanation:
we know that
The volume of the triangular prism is equal to

where
B is the area of the triangular base
H is the height of the prism
Convert 9 ft to yd
Remember that
1 ft=1/3 yd
9 ft=9*(1/3)=3 yd
Find the area of the base B

we have

substitute the values in the formula

