Objective question in Electrostatics

Three concentric metallic spheres A, B and C have radii a, b and c(a<b<c) and surface charge densities on them are sigma ,,-sigma and sigmarespectively. The valves of {{V}_{A}} and {{V}_{B}} will be
a) frac{sigma }{{{varepsilon }_{0}}}(a-b-c),,frac{sigma }{{{varepsilon }_{0}}}left( frac{{{a}^{2}}}{b}-b+c ight) b) (a-b-c),,frac{{{a}^{2}}}{c} c) frac{{{varepsilon }_{0}}}{sigma }(a-b-c),,frac{{{varepsilon }_{0}}}{sigma }left( frac{{{a}^{2}}}{c}-b+c ight) d) frac{sigma }{{{varepsilon }_{0}}}left( frac{{{a}^{2}}}{c}-frac{{{b}^{2}}}{c}+c ight)andfrac{sigma }{{{varepsilon }_{0}}}(a-b+c)