Read the passage from "The City Without Us" by Alan Weisman:
The notion that someday nature could swallow whole
something so colossal and concrete as a modern city
doesn't slide easily into our imaginations. The sheer titanic
presence of a New York City resists efforts to picture it
wasting away. The events of September 2001 showed only
what human beings with explosive hardware can do, not
crude processes like erosion or rot. The breathtaking, swift
collapse of the World Trade Center towers suggested more
to us about their attackers than about mortal
vulnerabilities that could doom our entire infrastructure.
And even that once-inconceivable calamity was confined
to just a few buildings. Nevertheless, the time it would take
nature to rid itself of what urbanity has wrought may be
less than we might suspect.
Which two ideas does this passage most clearly develop?

A. The footprint of humanity on the world is permanent; humans may fade, but the effects of our civilization are lasting.
B. From nature's standpointhumankind is a disease that must be purgedonly through natural processes can the Earth be repaired.
C. Nature can destroy creations that were thought indestructible; humans aren't as powerful as the forces of nature.
D. The contempt that humans show nature will come back to haunt us; natural processes are worthier of respect than technology