Question

cellular respiration is... the process by which cells break light down into energy. the process by which cells break down glucose into energy. the process by which cells communicate with other cells.

Explanation:

Cellular respiration is a biological process. It occurs in cells. The main substrate is glucose. Through a series of reactions, energy (ATP) is produced. The first option refers to photosynthesis (using light). The third option is about cell - cell communication mechanisms (like signaling molecules), not respiration.

Answer:

the process by which cells break down glucose into energy.