The correct option is C Lichen
A bare rock is invaded by crustose lichen that secretes the carbonic acid which in turn causes corrosion of rocky material, the corroded rocky particles, and decaying lichen stars formation of the first soil layer. A little soil and humus accumulation facilitate the invasion of foliose and fruticose lichen which in turn speed up the soil formation. The lichen and moss forms substratum for germination seeds/spores of herbaceous plants and algae. Thus the correct answer is option C.