The region bounded by y=ax and y=x2 for x≥0 is revolved about the x-axis, where a>0 is chosen so that the curves intersect only at (0,0) and (a,a2). If the volume of the resulting solid is 1564π cubic units, what is the value of a?
a) 2
b) 2
c) 432
d) (564)1/5