What are the three most important factors that affect the Earth's biomes?

Can someone me choose a broad topic and area of focus i am really doing this as a tally to see which one most people pick ok water pollution global warming endangered species atmosphere for the !

Which of the following regions suffers the most from acid rain? a. the area around vancouver c. the area below atlanta b. the area below detroit d. the area above montreal

Identify the youngest layer in the figure ( have to click one letter)