Hydrogen "burning" in stars is ________.
◦ an atomic reaction that fuses 4 protons to make a helium nucleus, releasing energy by converting mass to energy
◦ a chemical reaction that bonds hydrogen to oxygen to make water, which remains a gas because of the extremely high temperatures
◦ an atomic reaction that generates hydrogen by splitting helium atoms
◦ hydrogen atoms that combine with deuterium atoms to make HD complexes, and this reaction generates immense amounts of energy