What is the primary job of the digestive system?

The primary job of the digestive system is breaking down food and secreting waste. This process involves several stages, beginning with the intake of food, which is mechanically and chemically broken down into smaller molecules. These molecules are then absorbed into the bloodstream for use by the body, while the indigestible remnants are expelled as waste. The digestive system plays a critical role in converting food into energy, nutrients, and other essential components needed for bodily functions.

The other options do not accurately represent the core functions of the digestive system. Storing fat is a function associated with adipose tissue and liver, while regulating temperature pertains to the integumentary and endocrine systems, and transporting oxygen is a primary function of the circulatory system. Each of these systems plays a unique role in the body, but they do not encompass the primary responsibilities of the digestive system.