Correct Option: A  [ respiration ]
Remark:
Explanation: Respiration is a biochemical process in which food molecules (mainly glucose) are oxidized to release energy in the form of ATP (adenosine triphosphate). This energy is then used for various life processes such as movement, growth, repair, and maintenance. Respiration occurs in all living cells and takes place mainly inside the mitochondria.
Chemical Equation:
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (ATP)
In contrast, photosynthesis stores energy in glucose molecules, while respiration releases that stored energy for cellular use.