# Which of the following is true for london smog?

$\begin{array}{1 1}(a)\;\text{It occurs during warm weather}\\(b)\;\text{It is reducing in nature}\\(c)\;\text{It is a common feature over deserts}\\(d)\;\text{It contain oxides of nitrogen}\end{array}$

It is reducing in nature.
Hence (b) is the correct answer.