Coral Reefs Are Limited to Shallow Water,and There Is a Concern

Coral reefs are limited to shallow water,and there is a concern that rising sea levels will affect the reefs.This is because ______________.

A) they require the lower salinity found in shallow waters
B) there are more nutrients found in shallow water
C) their symbiotic zooxanthellae require light to survive
D) they require coastal upwellings of CO₂ in order to survive
E) it is too difficult for them to build reefs in deeper water