Which of the following groups of four animals all give birth to young ones?

Why do mammals lack mucus glands in their skin?

Which of the following is an oviparous 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.

Among the following,which one lays eggs and does not produce young ones directly?

Which of the following is the fastest running mammal?