Answer:
B). "A species of wasp that eats caterpillars is killed off."
Step-by-step explanation:
The short story "Top of the Food Chain" authored by T.C. Boyle highlights the selfish human faults and presents a social critique of the human tendency to defend or justify these faults lying within them.
As per the question, the action/event that occurs first in the story would be "a species of wasp that eats caterpillars is killed off" in order to exterminate the caterpillars. The rest of the options(collapsing of roofs, dying of cats, and flowing of cats from Australia) suggest an event followed by this one. Therefore, option B is the correct answer.