Chemical Equilibrium

According to Le Chatelier's principle, in the reaction $\mathrm{CO}(\mathrm{g})+3 \mathrm{H}_2(\mathrm{~g}) \rightleftharpoons \mathrm{CH}_4(\mathrm{~g})+\mathrm{H}_2 \mathrm{O}(\mathrm{g})$, the formation of methane is favoured by

(a) Increasing the concentration of CO

(b) Increasing the concentration of $\mathrm{H}_2 \mathrm{O}$

(c) Decreasing the concentration of $\mathrm{CH}_4$

(d) Decreasing the concentration of $\mathrm{H}_2$