AIIMS 2018 Botany Bioindicators MCQ Question

Lichens, which are symbiotic associations between fungi and algae, are sensitive to air quality, particularly to pollutants such as sulfur dioxide (SO₂) and nitrogen oxides (NOₓ). Their presence or absence in an ecosystem can indicate levels of air pollution, making them valuable bioindicators. Since options A, B, and C do not provide relevant information or alternatives regarding the role of lichens in monitoring air quality, they are not applicable in this context. Understanding the ecological significance of lichens helps highlight their importance in assessing environmental health.