You are among a group of ten very intelligent people in a psychology experiment.
If you press "Cooperate", you will get (3 * C) + (2 * D) dollars.
If you press "Defect", you will get (3 * C) + (2 * D) + 5 dollars.
In the formulas, C is how many of the ten people chose "Cooperate" and D is how many chose "Defect".
No one, except for the experimenter when they pay you, will know which you choose.
So... which do you choose? And why?