Which of the following methods can effectively reduce the concentration of photochemical smog in the atmosphere?

Using catalytic converters in automobiles
Planting certain trees such as Pinus, Juniperus, and Vitis
Both (A) and (B)
Encouraging formation of stratospheric clouds

Correct answer: Both (A) and (B)

Solution

Catalytic converters in vehicles reduce the primary precursors (NOx and unburned hydrocarbons) needed to form photochemical smog. Certain plants — Pinus, Juniperus, Vitis — absorb ozone and PAN, thereby reducing already-formed smog. Both strategies are recognized remedies.

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