Explanation
Scrubbers are used to control particulates and acid gases leaving the incinerator.
Scrubbers are air pollution control devices that use liquid to remove particulate matter or gases from an industrial exhaust or flue gas stream. This atomized liquid (typically water) entrains particles and pollutant gases in order to effectively wash them out of the gas flow.
Scrubbers can also remove or neutralize corrosive gases like hydrochloric acid (HCl) or sulfur dioxide (SO2) by using solutions of reagents that specifically target certain compounds.
Therefore, the correct answer is (a) Particulates.