Answer:
B. 15 ft^3
Explanation:
The volume of a pyramid is given by the formula ...
V = (1/3)Bh
where B represents the area of the base, and h represents the height.
The base is apparently a rectangle, so its area is the product of its length and width:
B = L·W = (4.5 ft)(4 ft) = 18 ft^2
Then the volume is ...
V = (1/3)(18 ft^2)(2.5 ft) = 15 ft^3
15 cubic feet of sand will be needed to fill the base.