Because enzymes connect to their substrate through a lock-and-key system, where the shape of the substrate and the enzyme has to fit like puzzle pieces. Then only the enzymatic reaction can occur.
Each of these animals have adapted in very similar ways to similar habitats. This us similar to a homologous structure, but that is a term used for the presence of similar bones.
Cellular respiration input: pyruvate (partially oxidized glucose), ADP, and inorganic phosphorus. Output: ATP, carbon dioxide, and water. Photosynthesis input: water, carbon dioxide, and photon energy. Output: Oxygen and glucose.
I think it's:
B- reproductive
