What are warm-blooded animals called?

External ears or pinnae are characteristic features of which group of animals?

Which among these is the correct combination of aquatic mammals?

The lower jaw of a mammal is made up of:

Which one of the following is an egg-laying mammal?

Given below are statements $X, Y,$ and $Z$ regarding the duck-billed platypus. Select the correct option based on these statements.
$X =$ It is an oviparous animal.
$Y =$ It has a four-chambered heart and the aortic arch curves to the right.
$Z =$ It is a mammal.