B. Interactions . Stress interrelationships among environmental spheres. Hard to change one thing without changing many others. The earth is constantly changing . Recognize that change is the norm, from time scales of seconds to millions of years.
Nothing stays the same forever.
The Universe as we know it is comprised of mainly empty space, plus millions of galaxies. Each galaxy contains billions of stars, some young, some old. Among these galaxies is the Milky Way, a spiral galaxy with a dense central cluster of stars. It is our Sun. The third planet out from the Sun is the Earth.