Answer:
1) Monotremes are mammals that lay eggs. The only monotremes that are alive today are the spiny anteater, or echidna, and the platypus. These mammals are really different from other mammals. Their body temperature is lower than most warm-blooded animals, a feature that has more in common with reptiles. Their name comes from the fact that they have only one body opening for both wastes and eggs to pass through.
2) Marsupial mammals give birth to babies that are not completely developed. The babies are very tiny. The babies then crawl up the fur on the mother's belly into a pouch on the outside of the mother's abdomen. The babies drink milk from the mother and continue to develop inside the pouch. Koalas, kangaroos, wallabies, and opossums are some of the better-known marsupials.
3)A placental mammal develops inside its mother's body until its body systems can function on their own. The name of this group comes from the placenta, an organ in pregnant female mammals that passes materials between the mother and the developing baby. Food and oxygen, carried by blood, pass from the mother to the baby through the placenta. Most mammals, including humans, are placental mammals.
Explanation:
