The second graph or the letter B
The answer is B. The values of y must only be positive because it is equal to
The other options states that the values of y could be negative which is why it is wrong.
The volume of a cylinder is
V=hpr^2 in this case h=40, r=20/2=10, and we will approximate pi as 3.14 so:
V=40(3.14)(10^2)
V=12560 ft^3