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According to paragraph 3, how do seagrasses affect the nutrient supply in the ecosystem? A. Because of their high rate of metabolism, they consume a large percentage of the available nutrients. B. They attract various species of algae and bacteria that produce high nutrient concentrations in the water column. C. They take up carbon and other nutrients trapped on the sea bottom and bring them back into use. D. Through anaerobic processes at their roots, they produce a very nutrient-rich sediment.