Explain how limbless salamanders evolved according to Darwin's theory?

Question

Although most salamanders have four legs, the aquatic salamander

shown below resembles an eel. It lacks hind limbs and

has very tiny forelimbs. Propose a hypothesis to explain how

limbless salamanders evolved according to Darwin's theory of

natural selection?

Answer 1

The limbless salamander is adapted to burrowing in the mud. Limblessness is more advantagous. This is an example of natural selection.  

Answer 2

Heres the answer, it didn't.  It was created to be a salamander therefore, it has always been a salamander and will always be a salamander.  Get it.  Got it?  Good, move on with life.

Answer 3

Because you don't need to support your own weight in water, extra limbs would only drag you down. Any salamander with a birth defect of having smaller limbs would be able to swim faster and survive better, and be more likely to pass this on to their offspring. Eventually most of the salamanders would have smaller limbs.