Correct Option: C

Lichens typically grow in harsh environments in nature. Most lichens, especially epiphytic fruticose species and those containing cyanobacteria, are sensitive to manufactured pollutants. Hence, they have been widely used as pollution indicator organisms. Lichens are symbiotic associations of a fungus with a photosynthetic partner (called a photobiont or phycobiont) that can produce food for the lichen from sunlight.