Consider the following reactions in which all the reactants and products are present in gaseous state
$$2xy \rightleftharpoons x_2 + y_2 \quad K_1 = 2.5 \times 10^5$$
$$xy + \frac{1}{2}z_2 \rightleftharpoons xyz \quad K_2 = 5 \times 10^{-3}$$
The value of $$K_3$$ for the equilibrium $$\frac{1}{2}x_2 + \frac{1}{2}y_2 + \frac{1}{2}z_2 \rightleftharpoons xyz$$ is :

A

$$2.5 \times 10^{-3}$$

B

$$2.5 \times 10^{3}$$

C

$$1.0 \times 10^{-5}$$

D

$$5 \times 10^{-3}$$