Answer the following question given this paragraph: 

Therian mammals are viviparous. They give birth to an embryo or infant rather than laying eggs. The female reproductive system of a therian mammal includes a uterus and a vagina. There are two groups of therian mammals: placental mammals and marsupials.


Q: What are the two groups of therian mammals?

 Choices:

- felines and canines

- monotremes and mollusks

- dolphins and whales

- placental mammals and marsupials

A:
placental mammals and marsupials
