What is the purpose of using subheadings as a text feature in your writing?

Read this passage from alan weisman's "the city without us": he props his running shoe against the whitish bark of a chinese amur cork tree, growing among the last of the hemlocks. "this may sound blasphemous, but maintaining biodiversity is less important than maintaining a functioning ecosystem. what matters is that soil is protected, that water gets cleaned, that trees filter the air, that a canopy regenerates new seedlings to keep nutrients from draining away into the bronx river." now read this passage from jared diamond's "the ends of the world as we know them": both the shoguns and the japanese peasants took a long-term view: the former expected to pass on their power to their children, and the latter expected to pass on their land. . today, despite having the highest human population density of any large developed country, japan is more than 70 percent forested. what common theme of green literature is most strongly evident in both passages? a. in order to thrive in coming centuries, people must find viable alternatives to fossil fuels, such as coal. b. with careful and intelligent management, ecosystems can still thrive after human beings have changed them. c. in order meet their goals, environmentalists must people develop a personal desire to protect nature. d. there is no excuse for damaging the natural world, and anyone who does so will pay a steep price.