Which of the following method is used for the removal of SO₂ and NH₃ from the polluted air?

Wet scrubbers

The correct answer is Option (4) → Wet scrubbers

Wet scrubbers are a versatile and cost-effective pollution control technology designed to remove more than 99% of airborne particulate matter by moving contaminated gas through a liquid that captures pollutants. They work by trapping particulate matter in liquid droplets, which are then collected as the liquid dissolves or absorbs the pollutant gases. Wet scrubbers are especially effective at controlling inorganic fumes, vapors, and gases—such as chromic acid, hydrogen sulfide, ammonia, chlorides, fluorides, and sulfur dioxide (SO₂)—with typical removal efficiencies ranging from 95% to 99%.