A. Ozone, peroxyacetyl nitrate and No2
B. Smoke, peroxyacetyl nitrate and SO2
C. Hydrocarbons, SO2 and CO2
D. Hydrocarbons, ozone and SO2
The correct answer to the question: "Photochemical smog formed in congested metropolitan cities mainly consists of:" is "Ozone, peroxyacetyl nitrate and No2".