I would say the answer is A.
Fusion occurs constantly on our sun, which produces most of its energy via the nuclear fusion of hydrogen into helium. Neither do fusion reactions produce the large amounts of dangerous radioactive waste that fission reactions do. That's why it's such a dreamy source of energy.
Intermolecular forces in solids are strongest than in liquids and gases. Gases have the least strong intermolecular forces. Intermolecular forces are weak and are significant over short distances between molecules (determined by Coulomb’s law). The farther away from the molecules the weaker the intermolecular forces. Since molecules in solids are the closest, the intermolecular force between them as the strongest. Conversely, since gas molecules are farthest apart, the intermolecular forces between them are the weakest.