Answer:
Positive feedback.
Step-by-step explanation:
When a blood vessel is damaged, platelets attach and recruit more platelets to the area. These new platelets recruit even more, quickly increasing the number of platelets until the damage is sealed with a blood clot. This amplification is an example of positive feedback.
Positive feedback can be defined as the activities of the blood vessels and other organs of the body that enhances, catalyses and accelerates the clotting process until the flow of blood stops eventually.