The region R bounded by the curves x = y² and x - 2y = 15 is revolved about the line x = -. Use the washer method to set up an integral or sum of integrals that would give the volume of the solid:
a. ∫[0 to 4] π(15 + y²)² dy
b. ∫[0 to 4] π(15 - y²)² dy
c. ∫[0 to 4] π(15 - 2y)² dy
d. ∫[0 to 4] π(15 + 2y)² dy