Which mammal possesses both reptilian and mammalian characters?

Assertion : The duck-billed Platypus and the spiny ant-eater,both are egg-laying animals yet they are grouped under mammals.
Reason : Both of them have seven cervical vertebrae and $12$ pairs of cranial nerves.

Amongst the following mammals,which of the following is a monotreme?

Mammals that give birth to relatively undeveloped young and raise them in a pouch are called ....

Pick the mammal with a true placenta.

The Haversian canal is found in the bone of: