What is the fluid that circulates through the vessels in the body to carry substances to all body parts?

The correct answer is that blood is the fluid that circulates through the vessels in the body to carry substances to all body parts. Blood plays a crucial role in transportation within the body, including the delivery of oxygen and nutrients to cells and the removal of carbon dioxide and waste products. It consists of various components, including red blood cells, white blood cells, platelets, and plasma, all of which work together to maintain homeostasis and support bodily functions.

In contrast, plasma is a component of blood, specifically the liquid portion that carries cells and proteins, but it does not refer to the complete system of circulation. Serum is similar to plasma but lacks clotting factors and is often considered the fluid obtained after blood has clotted. Lymph is another fluid involved in the immune response and in returning excess tissue fluid to the bloodstream, but it does not circulate through the same network as blood. Thus, blood is the comprehensive term that encompasses the entire system of maintaining circulation and transporting essential substances throughout the body.