Which of the following is a vestigial organ?

Wings of pigeon,mosquito,and bat show:

$Ornithorhynchus$ is a connecting link between:

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.

The half-life of $C^{14}$ is approximately ..........

In $1938$,a coelacanth was found in