Agroup of organisms of a certain species that is
in one area at a given time is known as
a an ecosystem b a community c a population d a trophic level

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