Probley the one that says candy, because a trick is to put the object in the box ((in this situation)) that tells you where it is at, because most people will think you are trying to trick them, and will try to out trick you ((only to out trick themselves)) and pick the one that says Not Candy ((as in the example)), thinking you are trying to pull a fast one of them..
Its pretty basic.. If you have something in your left hand, and nothing in your right hand, and you hold your fists out balled up, and tell a person you have something in one of your hands, throw in a obvious indicator, like with a story about how your left handed, and have them choose a hand, most people will pick the right hand, because you are telling them something, in this case, that you are left handed, and they will think that there is no way you would put something in that hand, because you told them you are left handed to start..