Read the following excerpt from "The World Without Us" by Alan Weisman:With no dredging, Central Park's ponds and reservoir have been reincarnated as marshes. Without natural grazers — unless horses used by hansom cabs and by park policemen managed to go feral and breed — Central Park's grass is gone. A maturing forest is in its place, radiating down former streets and invading empty foundations.Which best explains how the structure of this passage supports the author's purpose?A.The passage traces several events in the order that they will occur to highlight how people have harmed the environment in Central Park.B.The passage describes how the absence of human activity will change Central Park to show that nature will eventually destroy what people have built.C.The passage compares the Central Park from before and from during a posthuman world to underscore that pollution levels will remain the same.D.The passage shows the effects of human activity on Central Park to prove that laws protecting the environment are necessary for human survival.