Which of the following is an egg laying mammal?
Platypus
The word mammal is derived from the Latin word 'mammae' meaning breast. They possess mammary glands which produce milk, used to feed their young ones. Most mammals are viviparous i.e. they give birth to young ones, while some mammals are oviparous i.e. they lay eggs. Platypus is an example of an oviparous mammal. Whereas kangaroo, whale and bat are viviparous hence the answer is a platypus.