The answer is: D. elastic rebound hypothesis.
Answer:
As an ecosystem, the Amazon is one of the most biodiverse places on earth. Over 3 million species live in the rainforest, and over 2,500 tree species (or one-third of all tropical trees that exist on earth) help to create and sustain this vibrant ecosystem. More and more, biodiversity is at risk.
Explanation:
As in 2009, there are approximately 20,000 cities or metropolitan areas in the United States.
