A coral reef is a complex [ecosystem] of calcium carbonate shells that are home to microbes, algae, invertebrates, and fishes, and its high productivity helps provide great species richness.
Answer:
C. Hypothesis
Explanation:
Hypothesis is a proposed explanation for a certain occurrence and when the explanation is conclusive, then it becomes a theory.
It help because if the the plouttion is because of water it will rain
all living things are composed of cells
cells are the basic units of structure and function in living things
all cells are produced from other cells
