Coral reefs share a symbiotic relationship with a type of algae called zooxanthellae. the hard exoskeleton that makes up a coral reef provides a safe habitat for zooxanthellae. in return, zooxanthellae use sunlight to make food for themselves and for the coral. one of many threats to coral reefs is sedimentation run-off. sedimentation run-off clouds the water, as well as changes its chemistry. if sedimentation run-off continues along coral reef coastlines, how would this most likely lead to the extinction of coral reefs? a. by blocking sunlight from reaching zooxanthellae, sedimentation run-off may deprive coral reefs of the nutrients they need. b. by causing zooxanthellae to rapidly increase in population, sedimentation run-off may greatly reduce the habitat available to coral reefs. c. by causing coral reef waters to become overly warm, sedimentation run-off may cause coral reefs to become overheated. d. by clouding the visibility of coral reefs from humans, sedimentation run-off may result in boats and ships destroying coral reefs.