Answer:
B. Secondary pollutant
Explanation:
A primary pollutant is directly emitted into the atmosphere. Volcano eruptions and emissions from cars can result in primary pollutants in the air.
Secondary pollutants are not directly put in the atmosphere. They are created when two or more primary pollutants in the atmosphere react. One example is smog.
Another example is acid rain. If sulphur dioxide, nitrogen dioxide and water react, then acid rain is formed. Therefore, acid rain must be a secondary pollutant.
The best answer choice is B. secondary pollutant
