Well, although an ADP is "phosphorylated" to add the inorganic phosphate (PO4) that makes it ATP, the process that provides all of the energy comes from C) the breakdown of food molecules.
In order to make 36-38 ATP per single glucose molecule, food must be catabolized (broken down) into its basic components (mainly glucose), then the energy released from C--C covalent bonds in glucose gets captured from electron carriers (NADH, FADH2) to transfer that energy into phosphorylating ADP into ATP.
