Question

polyps secrete calcium carbonate to form (1 point)
an exoskeleton.
a reef.
a coral.
a food source
check answer! remaining attempts 3

Explanation:

Coral polyps secrete calcium carbonate to form a coral (the hard structure that makes up coral colonies, and over time, with many polyps and their secretions, reefs form, but the direct secretion forms the coral structure itself). An exoskeleton is more associated with organisms like arthropods, a reef is a larger structure formed by many corals, and a food source is not formed by their secretion of calcium carbonate.

Answer:

B. a coral