Ans.
Platypus is an egg-laying mammalian species, which feeds its offspring milk like other mammals. Platypus shares features of both mammals (such as, presence of mammary glands and fur) and reptiles (such as egg laying and presence of egg shells), although it is classified with the mammals.
It is because, it shows more genetic similarity (around 82 percent similarity) with mammalian genome as compared to other vertebrates. Thus, the correct answer is option D).