When did the human population reach 500 million people?
A. 400 years ago
B. 1,000 years ago
C. 4,000 years ago
D. 10,000 years ago
Answer:A
When did the human population reach 500 million people?
A. 400 years ago B. 1,000 years ago C. 4,000 years ago D. 10,000 years ago