The answer is c. Fish and other aquatic life die off. Algal bloom occurs as the excess of nutrients. Algae use this increased nutrients to enhance their own growth. Soon, a great number of algae is present in the river. All function normally until a great number of algae die and decomposition begins. Oxygen is needed for decomposition and soon it will be depleted from a body of water. This will lead to the death of fish and other aquatic organisms that depend on oxygen.