Final answer:
The claim about opossums having a very long gestation period is false. Marsupials, including opossums, have short gestation periods and the young continue to develop in the mother's pouch afterward.
Step-by-step explanation:
The statement about opossums having a very long gestation period and then nursing their babies in a belly pouch for another long period is false. Marsupials, which include opossums, give birth to underdeveloped embryos after a relatively short gestation period.
These embryos then continue to develop and are nourished in the mother's pouch for several months. The mother's pouch provides a safe environment for the immature young, where they can attach to a nipple and receive milk until they are more fully developed and capable of surviving outside the pouch.