Question

Is there a id for each answer ? and  is it  in the functions defined ,which one ?thx

Answer 1

Besides jatin.soni answer, and more specifically, each post has an id, answers amongts posts being labelled with an 'A' type. Also you have a bunch of functions to handle these. Have a look there, mainly in the "Post management" section for what you want: http://www.question2answer.org/functions.php

Answer 2

Of course each answer has unique ID and you can find in a_list_item($a_item) where $a_item holds post id so you can use in that function something like below

$a_item['raw']['postid'];