What is a primary function of ATP in cellular activities?

Adenosine triphosphate (ATP) primarily functions as the energy currency of the cell. It plays a crucial role in providing the energy required for various cellular processes such as muscle contraction, nerve impulse propagation, and biochemical reactions. When ATP is hydrolyzed, it releases energy that can be harnessed for these processes, making it essential for maintaining cellular functions and enabling both anabolic and catabolic reactions.

In contrast to other options, stimulations of immune responses, regulation of blood pressure, and nutrient transport in the blood are important physiological processes, but they do not specifically relate to the direct energy supply within cells. ATP is distinctively involved in energy transfer and storage within the cellular context, which makes it indispensable for life at the cellular level.