The correct option is C Reptilia and Mammalia
Duck-billed platypus (Ornithorhynchus) is a connecting link between reptiles and mammals. It shows mammalian characters like mammary glands, hair, diaphragm, single aortic arch etc. It shows reptilian characters in having a large coracoid in pectoral girdle and in laying eggs with yolk and shell. Hence, option C is correct.