Answer:
The complement system or complement cascade is an essential part immune system that increases the ability of the immune cells such as phagocytic cells and antibodies to kill and remove foreign bodies such as microbes and removes the damaged or infected from the cells of an infected organism.
The complement system utilizes the classic pathway to destroy cell walls or membrane of antigen or microbes, however, it sometimes also use alternate pathway for certain organism
Large numbers of activated complement proteins are produced by the complement system that binds and, opsonizing microbes for internalization by phagocytes having receptors for a complement. It is important for innate defense