Which is an example of a social reason for voluntary migration

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.

What is unusual about the iraq mountains ,in spite of their old age?

Soil is made of air water organic material minerals weathered rock