What happens in a nuclear fusion reaction?
A.The nucleus of a larger atom splits into two nuclei of relatively similar size, which then lose their electrons and become anions.
B.The nucleus of a single heavy atom splits into two or more smaller nuclei that have relatively similar mass.
C.The nucleus of a heavy atom combines with the nucleus of a smaller atom, forming an atom with a larger nucleus.
D.The nuclei of two atoms with smaller mass combine to form a single atom with one larger nucleus.