Today, there are about how many people living on the earth?
3.4 billion
7.5 billion
9.0 billion
6.6 billion

Stages 1 and 4 of the demographic transition are similar in that

Why is the indus river so important to the people of pakistan?

What evidence does the writer give to support his argument about coral reefs? a) he speaks of the activities of coral polyps. b) he describes the composition of the great barrier reef. c) he emphasizes the ways in which coral reefs are fragile. d) he points out the ways that scientists do research on the reefs.