The C.G. of a solid hemisphere lies on the central radius 3r________________?

The C.G. of a solid hemisphere lies on the central radius 3r________________?

A. at distance — from the plane base 3r
B. at distance — from the plane base 3r
C. at distance — from the plane base 3r
D. at distance — from the plane base or
E. at distance — from the plane base