Which group includes kangaroo and opossum as examples?

• A. Monotremes
• B. Marsupials
• C. Placental mammals
• D. Reptiles

Answer: (B)

Marsupials are a group of mammals defined by giving birth to very underdeveloped young that finish growing in a pouch. Kangaroos and opossums exemplify this pattern, as their newborns crawl into a pouch and attach to a teat to continue development outside the womb. This reproductive strategy sets them apart from monotremes, which lay eggs, and from placental mammals, whose young develop longer inside the uterus connected to a placenta. Reptiles also don’t fit here since they are not mammals and have different reproductive modes.