Which system is responsible for circulating blood throughout the body?

The cardiovascular system is responsible for circulating blood throughout the body. This system consists of the heart, blood vessels, and blood, and it plays a critical role in transporting oxygen and nutrients to cells, as well as removing waste products like carbon dioxide. The heart acts as a pump that propels blood through a network of arteries, veins, and capillaries, ensuring that all tissues receive the necessary substances for proper functioning.

In contrast, the respiratory system is primarily involved in the exchange of gases, bringing in oxygen and expelling carbon dioxide but does not circulate blood. The lymph vascular system is responsible for the transportation of lymph, a fluid that helps fight infection and maintains fluid balance in the body, and is separate from blood circulation. The endocrine system regulates bodily functions through hormones but does not have a direct role in the circulation of blood. Thus, the cardiovascular system is the correct choice for its function in blood circulation.