$$A_g \rightleftharpoons B_g + \frac{C}{2}_g$$. The correct relationship between $$K_P$$, $$\alpha$$ and equilibrium pressure $$P$$ is

A

$$K_P = \frac{\alpha^{1/2}P^{1/2}}{2 + \alpha^{1/2}}$$

B

$$K_P = \frac{\alpha^{3/2}P^{1/2}}{(2 + \alpha)^{1/2}(1 - \alpha)}$$

C

$$K_P = \frac{\alpha^{1/2}P^{3/2}}{2 + \alpha^{3/2}}$$

D

$$K_P = \frac{\alpha^{1/2}P^{1/2}}{2 + \alpha^{3/2}}$$