Question

which of the following is not one of the three major structures of coral reefs?
a. planulae
b. fringing
c. barrier
d. atoll
please select the best answer from the choices provided

Explanation:

Fringing, barrier, and atoll are the three major types of coral - reef structures. Planulae are the free - swimming, ciliated larvae of cnidarians (including corals), not a coral - reef structure.

Answer:

A. planulae