How many countries are there in asia?

Were the first to arrive in nowth america. asian french

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.

Which water sources contribute to a river system? check all that apply. groundwater lakes rivers streams watersheds