Why does the tadpole's tail will be gone when it reaches its frog stage?

Question

Why does the tadpole's tail will be gone when it reaches its frog stage?

Answer 1

it only uses the tail to swim because it is confined to water a frog loses its tail because it now has legs which he can function in water with and on land

Answer 2

Its legs have become developed to be it's source of transportation and no longer needs the tail.

Answer 3

because if the frog still has the tail,it would be much harder to jump from place to place.