Parasitoid Wasps Are Sometimes Involved in a Plant's Defensive Response

Parasitoid wasps are sometimes involved in a plant's defensive response.In what way are the wasps helpful to the plant?

A) The wasps respond to a chemical the plant gives off when wounded, and the wasps lay their eggs on the caterpillar that wounded the plant.
B) The wasps live in hollow thorns of the plants, and attack the plants' predators.
C) The wasps stimulate the production of alkaloids the plants use for defense.
D) The wasps enhance the plants' hypersensitive response.