At a given temperature, K1, K2 and K3 are equilibrium constants for the following reactions 1, 2, 3 respectively. CH4(g) + H2O(g) ⇌ CO(g) + 3H2(g), CO(g) + H2O(g) ⇌ CO2(g) + H2(g) CH4(g) + 2H2O(g) ⇌ CO2(g) + 4H2(g) Then K1, K2 and K3 are related as ?
A. K3 = K1.K2
B. K3 = (K1.K2)0.5
C. K3(K1+K2)/2
D. K3 = (K1.K2)2