What was the world population at the beginning of the 21st century?
A. Over 2.1 billion
B. Over 6 billion
C. Over 7.2 billion
D. Over 9.1 billion
Answer:B
What was the world population at the beginning of the 21st century?
A. Over 2.1 billion B. Over 6 billion C. Over 7.2 billion D. Over 9.1 billion