Question

why does the presence of predators help keep an ecosystem stable?
a. the predators decrease biodiversity.
b. the predators keep prey populations balanced.
c. the predators stop species from competing.
d. the predators eat the keystone species.

Explanation:

Predators prevent prey overpopulation. This balance maintains ecosystem stability. For example, wolves (predators) control deer (prey) numbers, preventing over - grazing. Biodiversity is often maintained (not decreased as in A). Species still compete (C is wrong). Predators don't typically eat keystone species (D is wrong).

Answer:

B. The predators keep prey populations balanced.