The correct option is B It is a multi step reaction
The cleavage of bonds of complex organic compounds in the presence of oxygen within the living cells leads to the release of a considerable amount of energy. This process is known as respiration. The energy is released in a series of slow, stepwise, enzyme controlled reactions, and it is trapped as chemical energy in the form of ATP. Glycolysis, oxidative decarboxylation, Krebs cycle, electron transport chain reaction and oxidative phosphorylation are the various stages of aerobic respiration. Thus, it is a multi step reaction.