Question

Water pollution can be stopped best by:
(A) Treating effluents to remove injurious chemicals
(B) Rearing more fishes
(C) Cultivating useful water plants
(D) Spraying with DDT

Answer 1

Hint: Numerous diverse contaminants, such as petroleum, toxic waste, and disease-causing bacteria, can lead to water pollution. Septic tanks, filter beds, decomposition ponds, and sewage oxidation ponds have all been developed to control water pollution.
Step by step solution:
The discharge of pollutants into water bodies that render the water unfit for human use and disturb aquatic ecosystems is referred to as water pollution. Water contamination occurs when chemicals contaminate water sources and render the water unfit for swimming, drinking, cleaning, or other uses. In addition to chemicals, waste, bacteria, and parasites, pollutants also include. Water becomes contaminated by all types of pollutants eventually.
Spraying DDT can lead to biomagnification which means further water pollution so option (D) is incorrect.
Plants cannot be cultivated in polluted water because they won't be able to grow due to contamination so, option C is incorrect.
Algae and bacteria are growing in luxuriant abundance in these oxidation ponds. Anaerobic bacteria use the O₂ released by algae to break down sewage.
So, option (A) is correct.
Note: Discharging effluents directly without treating them can lead to the presence of harmful substances which can significantly cause water pollution. Proper treatment can result in a lowering of pollution.