Directions: Read each sentence below. Type R if it refers to rainforest, C if coral reefs and M if mangroves. Type your answer on the blank before the number. _______16. The first line of defense for coastal communities. _______17. The lungs of the planet _______18. Their role is to absorb carbon dioxide and produce oxygen. _______19. Nursery grounds for economically important fish species. _______20. We can protect this by discouraging people from collecting coral for ornamental purposes.