Answer: a.Oxygen combines with carbon of simple sugar.
In cellular respiration, the presence of oxygen results in the break down of glucose molecule is broken down into carbon dioxide and water. The energy is required for this process that transforms the glucose in the form of ATP. The oxygen is required to produce ATP. Later on more energy is produced by the process of oxidative phosphorylation. ATP molecules transfers energy to the cells, which are the chief source of energy and also get used up in this process.
