Protista
Plantae
Algae
Monera
According to five kingdom classification, kingdom Monera consists of prokaryotes and protists include unicellular eukaryotes. Chlamydomonas and Chlorella were earlier placed in algae but as the criteria for classification have changed and as the knowledge about evolution developed, now they are placed under the kingdom Protista. New classification takes into account the morphology and physiology and reproductive similarities. Thus the correct answer is option D.