A list of air pollutants is given below:

Q. A list of air pollutants is given below:

i. Sulphur dioxide

ii. Carbon monoxide

iii. Radioactive substances

iv. Sulphuric acid

Which of these are ‘primary’ pollutants?

1. i and ii only
2. i, ii and iii only
3. iii and iv only
4. i and iv only

Answer: i, ii and iii only