When they were first discovered in Australia in 1798, duck-billed, beaver-tailed platypuses so defied categorization that one scientist assigned them the name Ornithorhynchus paradoxus: “paradoxical bird-snout.” The animal, which lays eggs but also nurses blank young with milk, has since been classified as belonging to the monotremes group.
Which choice completes the text so that it conforms to the conventions of Standard English?