Answer:
The correct answer is - 2. Helium.
Step-by-step explanation:
Nuclear fusion is a reaction that involves the fusion of two or more atomic nuclei to make different atomic nuclei with subatomic particles and releases a huge amount of energy.
Two hydrogen molecules with one proton and one neutron fused together to make a larger helium molecule with two protons and two neutrons and release a huge amount of energy.
1H^2+1H^2 ====> 2He^4 + energy