The equilibrium constants for the following three reactions $(i)$,$(ii)$,and $(iii)$ are given as:
$(i)$ $CO_{(g)} + H_2O_{(g)} \rightleftharpoons CO_{2(g)} + H_{2(g)} \quad K_1$
$(ii)$ $CH_{4(g)} + H_2O_{(g)} \rightleftharpoons CO_{(g)} + 3H_{2(g)} \quad K_2$
$(iii)$ $CH_{4(g)} + 2H_2O_{(g)} \rightleftharpoons CO_{2(g)} + 4H_{2(g)} \quad K_3$
Which of the following relations is correct?

• A
  $K_3 = K_1 \times K_2$
• B
  $K_3 = K_1 / K_2$
• C
  $K_3 = K_2 / K_1$
• D
  $K_3 = K_1^2 \times K_2$