# Which of the following is not a primary pollutant

$\begin{array}{1 1}(a)\;SO_2\\(b)\;NO_2\\(c)\;PaN,O_3\\(d)\;CO_2\end{array}$

$PaN,O_3$
Peroxyacetyl nitrate (PAN) and ozone are the two important secondary photochemical air pollutants found in the urban atmosphere
Hence (c) is the correct answer.
edited Feb 26