(C) is the right answer.
Taxonomic studies consider a group of individual organisms with fundamental similarities as a species. Genus comprises a group of related species which has more characters in common in comparison to species of other genera. Family, has a group of related genera with still less number of similarities as compared to genus and species. Order being a higher category, is the assemblage of families which exhibit a few similar characters. Classes comprising animals like fishes, amphibians, reptiles, birds along with mammals constitute the next higher category called Phylum