How do you choose 'The Best Response'?

hey on every user name u will saw a dark blue link "mark as best response" another way is press ctrl+f and search for best.

I choose the response that stayed with the discussion and the one that gave me the best answer. Sometimes if I only get 1 or 2 answers I will choose the first one because they took the time to answer first. Best Response is important to payment I think. So you can give me a + rating and a best response if you like. :)