The correct option is B sulphur dioxide
Acid rain is more properly called acidic deposition, which occurs in both wet and dry forms. Wet deposition usually exists in the form of rain, snow, or sleet but also may occur as fog, dew, or cloud water condensed on plants or the earth's surface. Dry deposition includes solid particles (aerosols) that fall to the earth's surface. Condensation of fog, dew, or cloud water is referred to as occult deposition.
The most common acidic substances are compounds containing hydrogen, sulphates, and nitrates. The chief source of these compounds is the combustion of fossil fuels such as coal, petroleum, and petroleum by-products, primarily gasoline.
Hence, acid rain is caused when air polluted by a large volume of sulphur dioxide.