Answer:
1. Yes, I think human population is a concern because of the strain it will put on farmers and food workers to produce an adequate amount of food for the extra population. Also, there is alreadfy low livable space in every country, the standard of living will go down in The United States if there is a larger population, earth is already overpopulated.
Explanation:
Im not sure if this is what you specifically need, but this is just my response to the question, "Do you think human population growth is a concern in the United States?"
Answer:
Energy does not cycle the way nutrients and atoms do. Energy enters the ecosystem from the Sun and exits after the organisms have taken as much as they need. Organisms release energy back into the biosphere as heat.
The correct answer I think is D. The nucleus
Cratering, Erosion, Volcanoes and Weathering