When fossil fuel is burnt nitrogen and dioxygen combine to yield significant quantities of nitric oxide (NO) and nitrogen dioxide (NO2) as given below:
N2 (g) + O2 (g) → 2NO (g)
2NO (g) + O2 (g) → 2NO2 (g)
Higher concentrations of NO2 damage the leaves of plants and retard the rate of photosynthesis.
Hence, option (b) is the correct answer.