Which group includes bat and whale as examples?

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

Answer: (C)

Bats and whales are grouped as placental mammals because their young develop inside the mother's uterus and are nourished through a placenta during a lengthy gestation. This placenta-and-uterus connection allows the offspring to grow considerably before birth, which is a hallmark of placental mammals. Monotremes lay eggs, so they don’t share this in-utero development, and marsupials give birth to very undeveloped young that finish growing in a pouch rather than inside the uterus. Reptiles are not mammals at all. So the best group for both is placental mammals.