Answer:
a. ATP.
Step-by-step explanation:
The Adenosine triphosphate (ATP) molecule is also known as the energy currency for all known life forms because its phosphate bonds can support endergonic chemical reactions in the cells. The ATP molecule is composed of a nitrogenous base (adenine), a sugar ribose, and three phosphate groups. The phosphate bonds of this molecule can be broken (hydrolyzed) in order to produce energy which is then used to drive metabolic processes (e.g., chemical synthesis, nerve impulse propagation, muscle contraction, etc).