The correct answer is A. Respiration.
Respiration is a metabolic process that releases energy from organic molecules, such as glucose, in order to produce ATP (adenosine triphosphate). ATP is the main energy currency of the cell, and it is used to power a variety of cellular processes, including muscle contraction, nerve impulse transmission, and protein synthesis.
Photosynthesis is a process that uses light energy to convert carbon dioxide and water into glucose and oxygen. This process is carried out by plants and other photosynthetic organisms, and it is the basis of the food chain.
Ingestion is the process of taking food into the body. This process is carried out by the mouth, esophagus, stomach, and small intestine.
Absorption is the process of taking nutrients from food into the bloodstream. This process is carried out by the small intestine.
In conclusion, respiration is the process in which energy is released. The other options are not processes that release energy.