There are over 6 billion humans on Earth presently, but less than 50 years ago, in 1960, according to the graph in the text on page 10, there were…

8. There are over 6 billion humans on Earth presently, but less than 50 years ago, in 1960, according to the graph in the text on page 10, there were only aboutA. 2 billionB. 3 billionC. 4 billionD. 5 billion