What is the body structure for chemical levels?

Moving down the ramp from 6 meters to

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

Based on her survey, which advertising mediums will work best to publicize leslie's in-store specials?