Agroup of students are studying the earth's mantle. they discover that the mantle is constantly moving. which of these most likely causes the movement of the mantle?

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.