Right choice is (c) Increase in water quality
For explanation I would say: Increase in water quality helps in maintaining a healthy aquatic ecosystem, whereas, Algal blooms causes the reduction in nutrient quality of the water which affects the biological life in water, aquatic organism consumed by humans may cause adverse health issues, nitrogen and phosphorus in aquatic ecosystem leads to eutrophication which leads to algal blooms and other adverse conditions and hence, reduction in marine life.