Which of the following organs is $NOT$ vestigial in humans?

Which one of the following is $NOT$ an example of analogous organs?

Choose the correct statements with reference to organic evolution.
$I.$ Flippers of whale and wings of bat exhibit analogy.
$II.$ Wings of butterfly and wings of bird exhibit homology.
$III.$ Organs with dissimilar structure are called analogous organs.
$IV.$ Organs with similar structure and origin are called homologous organs.

Flippers of a seal are:

The forelimbs of a cat and a lizard are used for walking. The forelimb of a whale is used for swimming,and the forelimb of a bat is used for flying. These are examples of:

The study of rudimentary (vestigial) organs is known as: