137.Organisms which are indicator of SO 2 pollution of air (a) mosses (b) lichens (c) mushrooms (d) puffballs.
Option B Lichens are found in Artic Tundra region where no other plant can grow. Lichens prefer to grow in pollution free environment. They are often used as a indicator of pollution and also they are very sensitive to SO 2 . They are first to die in a polluted environment (more SO 2 ).
