In Riccia, the sporogonium which is the sporophyte individual differs from the thallus (gametophytic plant) in structure, function and genetic constitution as well. The thallus is green in colour and autotrophic. The sporogonium has no colour and is heterotrophic in its nutrition. The thallus represents the haplophase where as the sporogonium represents the diplophase. Unlike other liverworts, the embryo, sporogonium and spore mother cells in Riccia do not develop chloroplasts. The sporophyte remains totally dependent on the thallus for food materials, water and minerals in solution.
So, the correct answer is 'Sporophyte is parasitic over gametophyte'
