The correct option is B Respiration
The process of acquiring oxygen through breathing and making it available to cells for the process of the breaking down of organic substances into simpler compounds called respiration. During respiration, the food materials are oxidised (degraded). During this reaction, energy is released from the food and it is stored in a special chemical (or) biological substance called ATP (Adenosine triphosphate). The energy of ATP is utilised for the various activities of the cells.