Question: Fact 1: Many corals secrete an exoskeleton that builds up to become a coral reef. Fact 2: An insect has a hard outer covering called an exoskeleton. Given the two facts above, answer the question "Many corals secrete what to form a coral reef?" with the following options: - Chlorophyll - salt and water. - The area was once underwater - Chemical energy - aqueous solution - Organic compounds - gastropod shells - hard outer covering
Answer:
hard outer covering