Two conducting concentric , hollow sphere A and B have radii a and b respectively with A inside B . Their common potentials is V . A is now given some charge such that its potential becomes zero . The potential of B will now be

Question

$(a)\;0\qquad(b)\;V (1-\large\frac{a}{b})\qquad(c)\;\large\frac{V_{a}}{b}\qquad(d)\;\large\frac{V_{b}}{a}$