I WONDER - Why Do Kangaroos Have A Pouch?

Kangaroos are marsupials that give birth to underdeveloped babies called joeys. These joeys continue to grow outside the womb in a special pouch on the mother's belly, where they stay safe and warm. Joeys remain in the pouch for about 6 to 9 months, depending on the species, before they venture out into the world.

Describe the purpose of the pouch in female kangaroos.

What factors determine how long a joey stays in the pouch?