Answer
(e)
Work Step by Step
Secondary pollutants are not emitted directly, but form in the atmosphere from reactions of primary pollutants.
Nitrate ($NO_3^-$), ozone ($O_3$), and sulfate ($SO_4^{2-}$) are all secondary pollutants formed from $NO_x$, $VOC$s, and $SO_2$, respectively.
The answer is (e).
