26. Let S be the closed region in the first quadrant of the xy-plane bounded by y = sin(pi x/2) and y = x for 0 ≤ x ≤ 1. What is the volume of the closed region in R3 obtained by revolving S about the x-axis?
A. 2 - (pi /2) B. pi /6 C. pi /3
D. pi /2 E. (2pi )/3
The volume of a solid of revolution is found.