The equilibrium constant for the reaction $ A + 2B \rightleftharpoons 2C $ is 40. The Equilibrium constant for the reaction $ C \rightleftharpoons B + 1/2 A$ is

Question

(a) 1/40

(b)  $ (1/40)^{1/2} $

(c) $ (1/40)^2 $

(d) 40