What did one have to do to survive the “selection” in section five of Night?

In section five, Elie and his father face yet another "selection" while they are at the work camp of Buna. They narrowly survive the initial selection at Birkenau when a man tells them to lie about their ages. By section five, Elie and his father are badly weakened by lack of food and the number of beatings they have received. Elie ironically states that this selection was the SS's "New Year's Gift." The SS were...

In section five, Elie and his father face yet another "selection" while they are at the work camp of Buna. They narrowly survive the initial selection at Birkenau when a man tells them to lie about their ages. By section five, Elie and his father are badly weakened by lack of food and the number of beatings they have received. Elie ironically states that this selection was the SS's "New Year's Gift." The SS were looking to weed out the weakest of the men and these selections were a constant fear. In Elie's block, the Kapo looks to be helpful as he gives hints as to how one might avoid being selected and then liquidated. He advises them to move around ahead of time to work up some "color" and to run "as if the devil were after you" as they approach the SS doctors. He also tells them not to be afraid, which, of course, was virtually impossible after all they had witnessed. Fortunately, both Elie and his father survive this selection, partly due to the Kapo's advice, but probably more out of sheer luck.