Which of the following best describes the process of digestion?

The process of digestion fundamentally refers to the breakdown of food into smaller components that can be effectively absorbed by the body. This process begins in the mouth with mechanical and chemical digestion and continues through the stomach and intestines, where enzymes further break down complex food molecules into simpler ones such as amino acids, fatty acids, and simple sugars. This breakdown is crucial because it allows the nutrients from the food to be released and prepared for absorption into the bloodstream later in the digestive process.

The other options, while related to digestion, do not wholly encapsulate the definition. For example, the conversion of food into energy involves metabolic processes that occur after digestion, while the absorption of nutrients is a subsequent step that occurs after the food has been broken down. Excretion is the final stage of the digestive process and involves removing undigested or unabsorbed material from the body, which is also not a direct description of digestion itself. Therefore, the best description of digestion is its role in breaking down food into smaller, usable components.