What is the primary function of platelets in the blood?

The primary function of platelets in the blood is to cause blood to clot. When a blood vessel is injured, platelets are activated and begin to gather at the site of the injury. They adhere to the exposed tissue and form a temporary "platelet plug" to help seal the wound. This process is crucial in preventing excessive bleeding and initiating the healing process.

While transport of oxygen is primarily the role of red blood cells, fighting infections is a function of white blood cells, and carrying nutrients is mostly performed by plasma and various blood components, the specific role of platelets is central to hemostasis, the process by which bleeding stops. Thus, the correct answer emphasizes the unique and critical role platelets play in maintaining vascular integrity and responding to injury through the clotting process.