‘Green Muffler’ is related to

The correct answer is C) Noise Pollution. A green muffler is a dense belt of trees and shrubs planted along highways, railway lines, and around industrial units. The layered foliage absorbs sound, scatters it, and softens traffic and machine noise, much like a muffler reduces engine noise. The idea is a nature-based noise barrier, not an air or water treatment measure.

Why the others are wrong:

• A) Soil Pollution: Concerns contamination of land by pesticides, heavy metals, and solid waste. Trees may help soil, but the green muffler is defined by sound reduction.
• B) Air Pollution: Trees do cut particulate matter, but that is a separate function. The green muffler term refers specifically to acoustic absorption. Air pollution is governed by the Air (Prevention and Control of Pollution) Act, 1981.
• D) Water Pollution: Governed by the Water (Prevention and Control of Pollution) Act, 1974. It has no link to sound barriers.

Core concept: noise is regulated under the Noise Pollution (Regulation and Control) Rules, 2000 and the Environment (Protection) Act, 1986. For Mains, green mufflers fit into discussions on nature-based solutions and urban planning in cities like Lucknow and Delhi.

Trap: Aspirants see trees and think of air purification, then pick B. The question is about sound, not air.