The correct option is B Water Pollution
Adding manure is a natural way of increasing soil fertility and in turn, increasing yield. Fertilisers are artificially synthesized inorganic salts which also increase yield.
Although both have similar attributes, excessive use of fertilizers may result in their runoff into the nearby water bodies, resulting in water pollution. An increase in nitrogen content in water bodies leads to algal bloom and disrupts the delicate balance of aquatic life.