Both Corals and Calcareous Sponges Have Calcium Carbonate Structures

Multiple Choice

Both corals and calcareous sponges have calcium carbonate structures.What is the relationship between these two groups?

A) The calcareous sponges were ancestors of the corals.
B) The corals were ancestors of the calcareous sponges.
C) Both use the calcium carbonate to form a rock-like or crusty basal skeletal structure.
D) The corals are actually colonial forms of the independent calcareous sponges.
E) The sponges use calcium carbonate to form sharp spicules,while the corals independently use the same material to form a skeleton.