Why Don't We See More Plant Material Eaten by Herbivores

Question

Why don't we see more plant material eaten by herbivores?
A) Herbivore populations self regulate
B) Natural enemies reduce herbivore densities
C) Plants have chemical and mechanical defenses
D) a and b
E) b and c

Accepted Answer

Natural enemies (such as predators and parasites) help control herbivore populations, and plants have evolved various defenses (both chemical and mechanical) to protect themselves from being eaten. These factors combined explain why we don't see more plant material consumed by herbivores.