Answer:
a. a set of proteins involved in innate but not acquired immunity.
Explanation:
The complement system are a set of proteins or protein fragments that play a major role in the innate immune system. The complement system is involved in the defense of the body from foreign pathogen through specific plasma proteins that participate in leukocyte activation, chemotaxis and opsonization. In other words, they increase the ability of phagocytes and antibodies to mop up damaged cells and foreign microorganism, activate inflammation process.
Some of these proteins include complement component 3 (C3), complement component 9 (C9) and C1Q complex.
Introducing a predator means there will be less prey which will help balance the population of prey. Some predators may run out of food and there might be no prey left for them. If the prey were removed the predator population would decline.
Key is to lock as D. Substrate is to active site.
This might be a bad idea as a lot of animals live in wetlands