If we are UNSURE what our opponent is going to do, we should make the strategic choice that results in the average most favorable outcome. And this is where the "dilemma" in the prisoner’s dilemma comes into play. The BEST outcome is that we both go free. The WORST outcome is that you serve 6 years while Suspect B only serves 1. The dilemma is that the same action (staying quiet) on your part can result in both the best and the worse case outcomes; the only determining factor is your opponent’s decision. Since you cannot predict your opponent’s decision you should always:
A. Confess
B. Stay silent