Environmental Pollution

Major sources include vehicular emissions, industrial discharges, burning fossil fuels, and deforestation.

Step 1: Understanding air pollution.
Air pollution occurs when harmful substances such as smoke, dust, gases (SO , NO , CO), and industrial emissions contaminate the atmosphere.

Step 2: Checking each option.
- (a) In slum areas → Generally overcrowded and polluted due to poor sanitation and use of biomass fuels. Air pollution is present.
- (b) Adjacent to bus stations → Vehicle exhaust produces smoke and harmful gases like CO and NO , contributing to air pollution.
- (c) In areas of clean air → By definition, these are pollution-free regions, such as rural forests, mountains, or areas far from human activities. Hence, no air pollution occurs here.
- (d) In industrial areas → Industries emit smoke, chemicals, and particulate matter, which cause air pollution.

Step 1: Understanding acid rain.
Acid rain occurs when sulfur dioxide ( ) and nitrogen oxides ( ) are released into the atmosphere due to burning of fossil fuels, industrial emissions, and vehicular pollution. These gases react with water vapor in the atmosphere to form (sulfuric acid) and (nitric acid).

Step 2: Identifying the cause.
Since acid rain is formed from pollutants present in the atmosphere, its direct cause is air pollution.

Step 3: Eliminating incorrect options.
- (A) Water Pollution → Related to contamination of water bodies, not acid rain.
- (B) Noise Pollution → Unrelated to chemical changes in rainwater.
- (C) Air Pollution → Correct, as it involves and .
- (D) Solid Waste Pollution → Not connected with acid rain formation.

Step 4: Conclusion.
The main cause of acid rain is air pollution.