Which of the following phenomenon proves that viruses are living?

Lichens are composite organisms consisting of a fungus and a photosynthetic partner (algae), growing together in a symbiotic relationship Consider the following statements about lichensI. Lichen are very good air pollution indicatorsII. Algal partner and fungal partner live mutuallyIII. Algae prepares food for fungiIV. Fungi provides shelter and absorbs water and minerals for algal partnerWhich of the statements given above are correct?

Organisms which are indicator of $S{O_2}$ pollution of air

Organisms which are indicator of $S{O_2}$ Pollution of air.