A solid conducting sphere of radius `a` has a net positive charge `2Q`. A conducting spherical shell of inner radius `b` and outer radius `c` is concentric with the solid sphere and has a net charge `-Q`. The surface charge density on the inner and outer surfaces of the spherical shell will be
A. `- (2Q)/(4 pi b^(2)), (Q)/(4 pi c^(2))`
B. `- (Q)/(4 pi b^(2)), (Q)/(4 pi c^(2))`
C. `0 , (Q)/(4 pi c^(2))`
D. None of these