Phenetic Taxonomy (B)

Classifying by similarity is the basis of Phenetics, a school of taxonomy that ignores common descent (i.e. "true" branching diagrams) as "unknowable" and instead classifies species by their "overall similarity".

Under this scheme, illustrated here (B), similarities due to common descent and convergence have equal weight.

So in the trio crocodiles, true reptiles and birds, pheneticists would classify the crocodiles and reptiles together in the same grade because of their "overall similarities".