The equilibrium constant K for the reversible reaction $$A \rightleftharpoons B$$ is $$2 \times 10^3$$ at 350 K. The rate constants of the forward reaction in the presence and absence of a suitable catalyst at the same temperature are $$5 \times 10^4\ \text{s}^{-1}$$ and $$4 \times 10^{-6}\ \text{s}^{-1}$$ respectively. The rate constant of the reverse reaction in the absence of the catalyst is

A

$$2 \times 10^{-3}\ \text{s}^{-1}$$

B

$$2.5 \times 10^{-1}\ \text{s}^{-1}$$

C

$$1.6 \times 10^{-7}\ \text{s}^{-1}$$

D

$$1.25 \times 10^{-2}\ \text{s}^{-1}$$