Air pollution is caused by transport exhaust fumes and emission of gases like $$SO_2$$, $$CO_, NO_2$$ from industries. Similarly, water pollution is caused by _____________.
The correct option is A Sewage Human sewage is an important source of water pollution. If untreated sewage gets into rivers, microorganisms decompose it. They use oxygen from the water for aerobic respiration. As a result, there is less oxygen dissolved in water, so aquatic organisms such as fish and insects may be unable to survive. Like this, sewage is causing water pollution.