Which of the following best defines metabolism in the context of nutrition?

• A. The mechanical breakdown of food in the mouth and stomach without involvement of cellular chemical processes, specifically describing mastication and peristalsis as the exclusive sources of nutritional energy.
• B. The set of chemical reactions in cells that break down and use food molecules to release energy measured in calories.
• C. A group of voluntary behaviors such as exercise and eating patterns that determine overall energy balance but excludes biochemical reactions inside cells.
• D. The process by which the body stores dietary energy as large inert molecules without subsequent breakdown for immediate energy use, thereby describing only anabolic reactions and excluding catabolism.

Answer: (B)