Answer:
The correct answer is chordata.
Step-by-step explanation:
The Reptilia, Amphibia, Mammalia, and the Aves all come under the kingdom Animalia, and all are the part of the basal clade Chordata. This signifies that all these species during a certain point of their life exhibited a notochord. A notochord refers to a cartilaginous rod of skeleton that supports the body in all the embryonic and in some of the adult chordate animals.