What is the main function of the digestive system?

The primary function of the digestive system is breaking down food into nutrients for absorption. The process begins in the mouth, where food is mechanically mixed with saliva and broken down by enzymes. It continues in the stomach and intestines, where various enzymes and digestive juices further decompose food into its nutrient components, such as carbohydrates, proteins, and fats. These nutrients are then absorbed through the walls of the intestines into the bloodstream, where they can be distributed to various cells and tissues in the body for energy, growth, and repair.

The other options pertain to functions performed by different systems in the body. For instance, transporting blood throughout the body is a function of the circulatory system, while regulating body temperature is primarily managed by the integumentary and thermoregulatory systems. Providing structural support to the body is the role of the skeletal system. Thus, among the given choices, breaking down food into nutrients for absorption distinctly characterizes the digestive system's main purpose.