The correct choice is (a) Nitrogen
For explanation: The irritant red haze in traffic and congested paces is due to the oxides of nitrogen. Haze can refer to aerosols of the wet type that causes reduction in visibility. Nitrogen gas is abundantly found in the atmosphere. This nitrogen will combine with oxygen which is also present in the atmosphere and form nitrogen dioxide. Nitrogen gas has a deep red color. Now, nitrogen dioxide will combine with the aerosols and thus, form the red haze that occur in traffic and congested places.