Double vagina are found in

In all mammals, . . . . . . .

All mammals possess hair,except .........

Only left aortic arches are present in

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.

Which of the following characteristics is associated with the life of mammals?