Answer:
1
Step-by-step explanation:
The equation is already balanced, and on the left hand side (reactants side), we see that there's one CH4 molecule and 2 O2 molecules. We don't care about the O2 molecules in this case, so we turn our focus to the CH4 molecule. One CH4 molecule has one carbon atom and 4 H atoms, so we know that there's only one carbon atom on the reactants side.