[jQuery] Choose the best Selector

[Pedram]

Dear folk
consider the Below HTML Code

<div id="a">
  <p id="b">
    <input type="text" id="c" />
  </p>
</div>

I would like to have Input selecter
there are some ways which one has more speed and it is efficient

1- $("div#a p#b :text#c").val();
2- $("#a #b #c").val();
3.$("#c").val();
4-$(":text#c").val();
5-$(#a).children().children().val();
and .....

Regards Pedram