Some estimates put the first human settlements in the Amazon at 32,000 to 39,000 years ago. Since that time, Amazon people have developed lifestyles that are well integrated with the benefits and constraints of rainforests.
An estimated 7-10 million Amerindians (the term for American Indigenous peoples) lived in American rainforests, half of them in Brazil, at the time of European arrival. When Pizarro arrived in Peru, more land was under cultivation and more food was being produced in the Andean region than today.
The answer is 4. You round up one number when the decimal point is equal to or more than .5
After reviewing the graph you have given with the question, there are several reasons why carbon 14 can't be used to accurately determine the age of organic remains that are 1 million years old.
A few of the reasons are; Carbon-14 has a short half life, after 1,000,000 years there wouldn't be enough carbon 14, and too little of the original radioactive sample would remain. Any of these choices are correct for the answer to the question you asked.
