Answer:
Option C, to prevent excessive bleeding by forming a barrier at the site of a wound
Explanation:
A blood clot, also known as a thrombus, is a clump of blood cell fragments (i.e. thrombocytes, platelets) that bind together when enough trauma occurs to cause damage to the vasculature lying within and or beneath the skin. In order to stop blood loss (hemorrhage), the body recruits these platelets to "plug the hole" that the damage has caused, similar to applying spackle to a patch of drywall in need of repair. This process is called hemostasis.
Thus, the primary purpose of blood clots is to prevent excessive bleeding by forming a barrier at the wound site, option C.