Question

Which pair of characteristics are found in all mammals without exception?

• A. Hair and viviparity
• B. Viviparity and mammary glands
• C. Viviparity and internal fertilization
• D. Mammary glands and internal fertilization

Answer 1

The correct option is D Mammary glands and internal fertilization

• Aquatic mammals like seals, walruses and whales do not have hair on their skin. Hence, it cannot be considered a characteristic that is found in all mammals.
• Primitive mammals like platypus lay eggs and cannot be considered viviparous.
• All mammals have mammary glands for the production of milk to nurse newborns and show internal fertilization. Thus, these can be found in all mammals without exception.

So, the correct answer is option D.