Option A

“How do clear, and thus nutrient-poor, waters support such prolific and productive communities?” This is the first question that arises in the author’s mind when he thinks about the corals. On his intent to find out the answer, he discovered that the corals produce food for themselves through the zooxanthellae algae using the metabolic wastes of themselves and hence they actually thrive in water that are relatively low in nutrients. He also explains that human activities increase nutrient content in these waters and degradation of shallow waters and hence cause deterioration of coral reefs. So we can conclude that coral reef communities may actually be more likely to thrive in waters that are relatively low in nutrients.