Correct Option: CExplanation: Cryptograms are known as Pteridophyta. The dominant phase, in these plants, is sporophyte. This means a diploid multicellular stage in the present life cycle of a plant. The main body is differentiated into true stems, roots and leaves.. Found in cool, damp, and shady places because of the need for water for fertilization.Some plant-like selaginella and Salvinia, possess micro and macro-sized spores and are termed heterosporous. The spore germinates and gives rise to small but multicellular free-living, inconspicuous, mostly photosynthetic thalloid gametophytes called prothallus.Hence, A prothallus is a gametophytic-free living structure formed in pteridophytes.