Which of the following systems consists of the heart, blood, and blood vessels?

The circulatory system is responsible for the transport of blood, nutrients, oxygen, carbon dioxide, and hormones throughout the body. It comprises the heart, which pumps blood, and a vast network of blood vessels, including arteries, veins, and capillaries, which carry blood to and from various parts of the body. This system is crucial for maintaining homeostasis and ensuring that every cell receives the necessary substances to function.

The other systems listed do not share this specific composition and function. The respiratory system involves the lungs and airways and is primarily focused on gas exchange. The endocrine system is made up of glands that release hormones into the bloodstream, regulating various body functions. The nervous system involves the brain and nerves, responsible for coordinating and controlling bodily functions and responses. Each of these systems plays a critical role in maintaining overall health, but only the circulatory system is characterized by its direct involvement in the transportation of blood and its components.