Which one of the following animals has a well-developed canine?

Which of the following groups of four animals are viviparous?

$A$: The duck-billed platypus and the spiny ant-eater,both are egg-laying animals yet are grouped under mammals.
$R$: Both of them have seven cervical vertebrae and mammary glands without teats.

Oval,biconvex,and nucleated $RBCs$ are found in:

The characteristic feature of Eutherians is ......

In which of the following organisms are turbinal bones found in the nasal passage?