According to paragraph 5, fast-growing filamentous or coralline algae are usually the dominant algae on healthy coral reefs in part because they A. are not affected by noxious chemicals produced by other organisms B. are less attractive as food for sea urchins and fishes than bigger seaweeds are C. occupy the areas of coral reefs that have lower temperatures and less light D. can live in a wider variety of microhabitats than their competitors can