Based on the experiment scenario:
1. describe the control group.
2. describe the experimental group.
3. what variable is kept constant?
4. what variables are being
changed?

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