Please help me with this I'm very confused

Which of the following can be reduced by the use of renewable energy sources? a. social costs b. economic costs c. environmental costs d. all of the above select the best answer from the choices provided a b c d

Tropical rain forests support more species per unit area than any other terrestrial ecosystem. what is one way rain forests are important to the health of the biosphere?

The greenhouse effect a. something that has occurred for millions of years b. an unnatural phenomenon caused by humans that maintains earths temperature range. c. the results of the differences in the angle of the suns rays d. an unnatural phenomenon that causes heat energy to be radiated back into the atmosphere