Ravi has purchased an aquarium and was surprised to know that regular cleaning of aquariums is essential. Why does it have to be regularly cleaned?

1. ADead fish and plants may spoil the electric supply of the aquarium.
2. BDead fish and plants are decomposed by microorganisms and smell bad.
3. CDead fish and plants should be disposed of in the soil, not in water.
4. DDead fish and plants may spoil the aeration system of the aquarium.