Explanation:

- Acid rain is primarily caused by the presence of sulfur dioxide (SO2) and nitrogen oxides (NOx) in the atmosphere. These gases react with water, oxygen, and other chemicals to form acidic pollutants.

- Option 1: Sulphur dioxide pollution.

- This is correct as SO2 is a major contributor to acid rain.

- Option 2: Carbon monoxide pollution.

- CO pollution contributes less significantly to acid rain compared to SO2 and NOx.

- Option 3: Pesticide pollution.

- Pesticides are not related to the formation of acid rain.

- Option 4: Dust particles in the atmosphere.

- Dust does not directly cause acid rain.