Which of the following groups of four animals are viviparous?

Which characteristic is found exclusively in mammals?

The Haversian canal is found in the bone of:

Which animal is distinct in terms of embryonic development among mammals?

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.

Echolocation is found in