Answer: B - In biology, ATP most commonly stands for adenosine triphosphate. Adenosine triphosphate is an organic compound that is the source of energy for use and storage at the cellular level. The structure of ATP is a nucleoside triphosphate consisting of a nitrogenous base (adenine), a ribose sugar, and three serially bonded phosphate groups. For instance, photosynthesis transforms light energy into chemical energy stored in glucose. Cellular respiration then releases the energy from glucose to build ATP.