Aplant evolves a high level of poison to defend itself against insects. soon an insect that prefers to eat this plant evolves an enzyme that breaks down the poison. this is an example of:

coevolution

Explanation:

When two species evolve in a tandem manner because one species exerts a selection pressure on another is termed as coevolution. In coevolution the evolution of one species is reciprocated by the evolution of other species. Coevolution can occur between species that mutually depend on each other, are forming a host-parasite relation, are competing with each other or are in a prey-predator relationship.In the given case, it is mentioned that the plant is evolving to have a higher level of poison and this is in-turn causing the insect to evolve and produce an enzyme that can break down the poison, so the plant here is exerting a selection pressure on the insect and hence, is causing the insect to evolve as the plant evolves. Thus, the given scenario is an example of co-evolution.