Which of the following blood component forms a plug at the site of injuries?

The story behind the answer

Platelets are small cell fragments that rush to a damaged blood vessel, stick to exposed collagen, activate, and clump together to form a temporary “platelet plug.” They also release chemicals (like ADP and thromboxane A2) that recruit more platelets, and they help trigger the coagulation cascade that lays down fibrin threads to stabilize the plug into a firm clot.

Context tip: Aspirin works by inhibiting platelet activation (via thromboxane), which is why it can increase bleeding time. Contrast the options: red blood cells carry oxygen, white blood cells fight infection, and plasma is the fluid that transports nutrients and clotting proteins—but platelets do the plugging. Memory aid: “Plate-lets patch the plate (break) in the vessel.”