Three concentric spherical shells have radii a, b and c . . .

Question : Three concentric spherical shells have radii a, b and c (a<b<c) and have surface charge densities σ,-σ,σ respectively. If VA, VB and VC denote the potentials of the three shells, then for c=a+b, we have 

a) Vc=VB≠VA

b) Vc=VA≠VB

c) Vc=VB=VA

d) Vc=VA≠VB

Doubt by Jayant

Solution :