Question: You are presented with the question "Many corals secrete what to form a coral reef?" and the following answer choices: - Chlorophyll - salt and water. - The area was once underwater - Chemical energy - aqueous solution - Organic compounds - gastropod shells - hard outer covering Now knowing that many corals secrete an exoskeleton that builds up to become a coral reef and an insect has a hard outer covering called an exoskeleton, choose the best answer.
Answer:
hard outer covering