Which of the following is used as an atmospheric pollution indicator?

Lepidoptera are insects that include butterflies and moths.

Lichen is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship. Lichens grow in area which is not polluted, as lichens do not possess roots and air is their primary source for most elements. Hence Lichens are used as an atmospheric pollution indicator.

Lycopersicon is a genus in flowering plant family and contains 13 species of tomato groups.

Lycopodium is a genus of club mosses.

Hence the correct answer is option (b).