The answer is C.
As a science website says, "Scientists think they know why the Ancestral Puebloans disappeared. The primary culprit, studies suggest, was a megadrought that would have made it impossible to grow enough food to feed the tens of thousands of people living in the region."
If you didn't know, drought represents the lack of rain.
Because of how the earth revolves on its axis effects the weather at different places in earth but for green house its mostly because of pollution overheating the atmosphere and thinking our ozone layer so were not as protected from the sun and things in space.
A if I am correct please correct me if I am wrong
Your answer would be Charles Darwin and Alfred Russel Wallace.
Hope this helps!
