Answer:
a. ATP
Step-by-step explanation:
It is ATP which is used for energy in body. An ATP molecule has three components a sugar to which a nitrogenous base and a phosphate group is attached. There are three inorganic phosphorus atoms in the phosphate group and it is in the bonds of these inorganic phosphates high energy is stored. When these bonds break, energy is liberated which we use in our day to day activities.
As such NADH and NADPH molecules are also high energy molecules but we cannot use their energy directly. They have to be first converted into ATP and only then we can use their energy. Glucose is a sugar which has chemical energy stored in it but we cannot directly use the energy of glucose either. It is only when glucose is broken down through cellular respiration we obtain these high energy molecules NADH, NADPH and ATP. In short, glucose is the source of these molecules.