How long did it take the human population to double from 500 million to 1 billion?
A. 150 years
B. 300 years
C. 450 years
D. 600 years
Answer:A
How long did it take the human population to double from 500 million to 1 billion?
A. 150 years B. 300 years C. 450 years D. 600 years