A. An explosion caused by putting together two volatile chemicals B. The process of splitting nuclei to produce energy C. The process of turning matter into pure energy D. The process of combining lightweight nuclei to make heavier nuclei E. A process that only occurs in bombs
Nuclear fusion is a process in which the atomic nuclei that has a low atomic number fuses to form a much heavier nucleus through the release of energy. Basically this is the process of combining two or more lightweight nuclei in order to form one heavier nucleus.
Lighter elements like hydrogen and helium are generally more fusible. Heavier elements are subject to a different process call nuclear fission. During this process a heavier nucleus splits either spontaneously or on impact with another particle and releases energy this way.