Number 4 makes absolutely no sense. Even if the authors presumption is correct (i.e., that the opponent will not throw a rock), countering with a rock still giv

Number 4 makes absolutely no sense. Even if the authors presumption is correct (i.e., that the opponent will not throw a rock), countering with a rock still gives you only a 50% chance of winning and 50% chance of loss. If the presumption were correct, it would be better to counter with scissors. Then you get 50% chance of winning and 50%chance of tie.