Which group of organisms is characterized by the presence of external ear pinnae and hair on the body?

Choose the correct option for the following statements:
$(i)$ Animals that maintain a constant body temperature are called $cold-blooded$ / $warm-blooded$ animals.
$(ii)$ Mammals are $viviparous$ / $oviparous$ animals.

Bats belong to which order?

Complete the following analogy with respect to the habitat of mammals.
Fossorial mammals: $i$ :: Arboreal mammals: $ii$

The following statements regarding mammals are correct except:

Which of the following mammals lays eggs?