Read this passage from “The City Without Us” by Alan Weisman:

As if that weren’t enough, as the NYBG forest became an island of greenery surrounded by hundreds of square miles of gray urbanity, it became the primary refuge for Bronx squirrels. With natural predators gone and no hunting permitted, there’s nothing to stop them from devouring every acorn or hickory nut before it can germinate. Which they do.

Which statement best explains how irony is used in the passage?

A. the absence of predators and the banning of hunting have led to an explosion in the squirrel population.
B. regeneration of a forest is dependent on the germination of acorns and hickory nuts.
C. the existence of the forest is threatened, not by fungi, insects, or disease, but by the squirrels.
D. the survival of an oasis amid miles of concrete and steel is threatened by animals that make it their home.