Answer:
The complement system of defense is composed of proteins that are always present in the blood.
(A) It causes immediate pathogen lysis.
This statement describes the importance of this system in early pathogen defense.
Step-by-step explanation:
The "complement system" is the protein series found in blood plasma. They are not a part of induced immune response which is early.
"Barrier defenses" are part of defense mechanism of the body. It is like body continuously protects itself against the pathogens.
The complement system is very important because it destroys the pathogens and eliminate the infection. The phagocytic cells and antibodies help in clearing the damaged cells present in an organism with this way.