Final answer:
Feather is not part of the human body. Human beings are members of the phylum Chordata, which includes species with a dorsal hollow nerve cord, and vertebrates which develop a notochord during their embryonic stage.
Step-by-step explanation:
Out of the options provided, feather is not a part of the human body. In the context of the statements provided about chordates and vertebrates, it is true that the dorsal hollow nerve cord is part of the chordate central nervous system and, in vertebrate fishes, the pharyngeal slits become gills. However, it is not true that humans are not chordates because they do not have a tail. Humans are chordates and do have a tail during their embryonic development, which becomes the coccyx in adults. Furthermore, while vertebrates have a vertebral column, they also have a notochord during some point of their development, typically in the embryonic stage before it is replaced by the vertebral column.