The concentrations of A and B are 3M and 4M respectively in the state of equilibrium of A(g)+2B(g)⇌C(g) . After the equilibrium is attained, the volume of container is doubled so that equilibrium is reestablished and at this state [B]eq is 3M. The equilibrium constant KC for the reaction is :
a. 0.083
b. 12
c. 4
d. 0.25