In baseball if there is a runner on 1st and they steal after the pitch who covers 2nd the shortstop or the 2nd?

The player who is closed to the base. Sometimes you have a right batter and the second base is in the the middle and the short stop is close to the base therefore he covers the 2 base,or if you have a left bater and the short stop is in the middle them the second basememt is the one to cover the 2 base. Clear!!!