Answer:
A
Step-by-step explanation:
CH4 has one carbon atom and 4 hydrogens, making a total of 5. MgO has 1 magnesium atom and 1 oxygen atom, making for a total of 2. NO2 has one nitrogen and two oxygens, or a total of 3. Finally, SO2 has one sulfur atom and two oxygen atoms, or a total of 3 as well. Therefore, the answer is A. Hope this helps!