Which system is responsible for breaking down food into nutrients and waste?

The digestive system is specifically designed to break down food into its essential nutrients, which the body can then absorb and utilize. This system includes various organs such as the mouth, esophagus, stomach, intestines, and accessory organs like the liver and pancreas. Each component plays a vital role in the mechanical and chemical processes of digestion, converting food into smaller, absorbable molecules.

The digestive system's primary function is to ensure that the body receives the necessary nutrients for energy, growth, and repair, while also facilitating the elimination of waste products that result from this process. This makes it distinct from other systems mentioned, which have different primary roles. For instance, the muscular system facilitates movement but does not partake in digestion. The excretory system is involved in the removal of waste products from the bloodstream but does not directly break down food. The respiratory system’s main role is to facilitate gas exchange, specifically the intake of oxygen and the expulsion of carbon dioxide, separate from nutrient processing. Thus, the digestive system is the correct and relevant system for breaking down food into nutrients and waste.