Which of the following processes is most likely to multiply exponentially? A. An uncontrolled nuclear chain reaction B. A controlled nuclear chain reaction C. Nuclear fusion D. Nuclear decay

A nuclear chain reaction occurs when one single nuclear reaction causes an average of one or more subsequent nuclear reactions, thus leading to the possibility of a self-propagating series of these reactions. The specific nuclear reaction may be the fission of heavy isotopes (e.g., 235U). The nuclear chain reaction releases several million times more energy per reaction than any chemical reaction.