The right answer is mentionned on the picture.
Cellular respiration is the process of cellular metabolism that converts the chemical energy contained in nutrients into adenosine triphosphate. These processes involve a succession of chemical reactions forming metabolic pathways that belong to catabolism, that is, they consist in cleaving large biological molecules into smaller molecules, which releases energy as well as number of waste. These reactions are generally exothermic, i.e., they produce heat, most of them oxidation-reduction reactions. From this point of view, breathing is chemically related to a combustion of nutrients, acting as electron donors (reductant), in the presence of an electron acceptor (oxidant).
Breathing is one of the essential ways in which cells can produce metabolic energy for their development and activity.
