In which reactions will the equilibrium shift towards reactants

When the pressure is applied
A. C(s) + O2(g) <-> CO2(g)
B. CaCO3(s) <-> CaO(s) + CO2(g)
C. 2Mg(s) + O2(g) <-> 2MgO(s)
D. 2H2(g) + O2(g) <-> 2H2O(g)

According to le Chataliers principle increase in P must result in decrease of V . In case of gases V is proportional to moles.
Only in case 'B' there are no gases on L.H.S. and 1 gas on R.H.S. so it moves towards reactants. In all other cases no. of gases molecules are greater/ equal in reactants

B, as when pressure is increased the point of equilibrium moves towards the side with the lower number of gas molecules in order to reduce the pressure back towards normal