Answer:
The correct answer is the option: d. opossum.
Step-by-step explanation:
Hello! Let's solve this!
A placental mammal is a mammal that is viviparous and its young fully develops in the mother's womb.
Mammalian metatheria are those that develop inside the marsupial pouch.
An example of the latter are marsupials and among them the opossum.
So we conclude that the correct answer is the option: d. opossum.