Question

Assertion: Duck-billed platypus and spiny anteater, both are egg-laying animals, yet they are grouped under mammals.
Reason: Both have cervical vertebrae and twelve pairs of cranial nerves.
A. Both Assertion and Reason are correct and the reason is the correct explanation for the assertion.
B. Both Assertion and Reason are correct but Reason is not the correct explanation for the assertion.
C. Assertion is correct but the reason is incorrect.
D. Both Assertion and Reason are incorrect.

Answer 1

Hint: Mammals are usually viviparous, that means they produce direct young one and newborn feed on mother milk, along with such character several other mammalian characters are as follow:
The presence of hair on the body, mammary gland which produces milk after delivery of newborn, Presence of 7 cervical vertebrae and 12 pairs of cranial nerves.

Complete answer:
- Apart from viviparous nature, mammals also produce eggs through which newborn came into existence. The duck-billed platypus and the spiny anteater are oviparous reptile-like mammals that lay eggs.
- The spiny anteater appeared as porcupine, which possesses a long tongue that used to catch the ants, by inserting into the tiny hole of ants bill, it produces several eggs, which keep in their pouch until they hatched out.
- While in case of the duck-billed platypus is appeared as duck, due to their mouth is look like duck beak and their body is covered by hairy fur and webbed feet,
- The platypus has some characteristics common with reptiles like egg lying habit, reptilian-like the excretory system and some endoskeleton feature, this animal act as a connecting link between reptiles and mammals.
- Both animals have 7 cervical vertebrae and 12 pairs of cranial nerves. They belong to the subclass Prototheria of the class Mammalia.

Hence, the correct answer is option (B).

Note: Mammals are the warm-blooded animals which have hairy fur, mammary glands producing milk, they are homeotherms, most of the mammals are viviparous except few. This class animal is found in all types of habitats and is the most dominant animal and capable to learn due to their developed brain.