The correct option is C Lichens
Lichens stage is the first stage in Lithosere (or succession on bare rock). Bare rock is invaded first by crustose lichens e.g : Graphis, Rhizocarpon. They corrode the rock at places causing foliose lichen e. g : Parmelia, Dermatocarpon to invade and eliminate crustose lichens and creating conditions for invasion by mosses. In tropics, blue green algae are pioneers instead of lichens in lithosere.