Which of the following is a function of the circulatory system?

Which of the following is a function of the circulatory system?

• A. Regulates wake and sleep cycles
• B. Maintains water balance in the body
• C. Turns food into energy
• D. Carries blood to the cells

Answer: (D)

The circulatory system’s job is to move blood through the body, delivering oxygen and nutrients to every cell and removing waste products like carbon dioxide. This transport network ensures that tissues get what they need to function and helps regulate temperature and support immune responses. Because its primary role is to carry blood to the cells, this choice best describes what the circulatory system does. Other functions listed fall to different systems. Regulating wake and sleep cycles is controlled by the brain and endocrine system. Maintaining water balance is handled by the kidneys and related bodily processes. Turning food into energy describes digestion and cellular metabolism, which rely on circulation to deliver nutrients and oxygen but are not the circulatory system’s direct function.

The circulatory system’s job is to move blood through the body, delivering oxygen and nutrients to every cell and removing waste products like carbon dioxide. This transport network ensures that tissues get what they need to function and helps regulate temperature and support immune responses. Because its primary role is to carry blood to the cells, this choice best describes what the circulatory system does.

Other functions listed fall to different systems. Regulating wake and sleep cycles is controlled by the brain and endocrine system. Maintaining water balance is handled by the kidneys and related bodily processes. Turning food into energy describes digestion and cellular metabolism, which rely on circulation to deliver nutrients and oxygen but are not the circulatory system’s direct function.