What are the primary functions of the digestive system?

The primary functions of the digestive system encompass several critical processes that enable the body to intake, process, and utilize nutrients from food. The correct answer highlights these functions, which include food processing and storage, manufacturing of necessary bodily substances, absorption of nutrients into the bloodstream, re-absorption of water, and the elimination of waste products.

Food processing and storage refer to the physical and chemical breakdown of food items, which begins in the mouth and continues in the stomach and intestines. Manufacturing involves the production of enzymes and other substances necessary for digestion. Absorption is a key function where nutrients move from the digestive tract into the bloodstream, supplying the body with essential elements for energy, growth, and repair. Re-absorption, primarily occurring in the intestines, focuses on reclaiming water and certain minerals to maintain hydration and electrolyte balance. Finally, elimination is the process of expelling indigestible substances from the body.

In contrast, the other options address functions not primarily associated with the digestive system. For example, excretion and filtration relate more to the urinary system, while movement and sensation are general functions of the muscular and nervous systems, respectively. Digestion paired with respiration combines two distinct bodily systems—though related, respiration is primarily a function of