Fact 1: Corals form large colonies in shallow tropical water.

Fact 2: Corals Corals are in the polyp stage.

Given the two facts above, answer the question "Something in the polyp stage can form large colonies in shallow tropical what?" with the following options: 
- mountains
 - ice
 - porous
 - CO 2
 - complex
 - colonies
 - wetland
 - water


 

        water 