What Characteristics Place These Animals in the Same Group

What characteristics place these animals in the same group?

A) Cartilaginous skeletons, placental development, and internal fertilization
B) Shelled eggs, four- chambered hearts, and being endothermic
C) Moist skin, eggs with a jelly- like coating, lungs in their adult forms, and gas exchange through their skin
D) Ventral nerve cords and gills in their adult forms
E) Internal fertilization, cartilaginous skeletons, and four- chambered hearts