Question

Which is the part of the coral that is built up over thousands of years into a reef?

(1 point)
Responses

A
A

C
C

D
D

B

Answer 1

The part that forms the reef is the coral’s hard calcium‑carbonate skeleton (the stony/base structure), secreted by the polyps over thousands of years.

I can tell you which letter to pick if you upload the diagram or tell me which label names (or points to) the skeleton.