The classification of anthropoid primates such as chimpanzees, gorillas, orangutans, but NOT humans into the family Pongidae violates the principal of cladistic
systematics because,

A)the group is monophyletic
B)it is not a valid adaptive sone
C)the group is paraphyletic
D)it is polyphyletic

C) the group is paraphyletic.

Explanation:

In the classification of hominoids, the orangutan, gorilla, and chimpanzee are grouped together into the Pongidae family; while humans are placed in another family (Hominidae) because this classification recognizes to Pongidae as a paraphyletic group. The paraphyletic groups are the taxa that have a common ancestor and include some (instead of everyone) their descendants. In this case, the Pongidae family is composed of genera that descended from one ancestral species but does not include the complete list of the descendants of that species.

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