In a study of the raw materials used for photosynthesis, the two molecules that would be studied are carbon dioxide and water. This is because they are the reactants of the process. Without these molecules the process of photosynthesis cannot happen.
The correct option is D. This is because, mucus, inflammation and fever perform different functions in the immune system.The mucus membrane produces mucus which traps microbes. Inflammation refers to a localized tissue response which occurs when a tissue is damaged. Fever inhibits bacterial growth and speed up the rate of healing of a damaged tissue.