A Trigger Strategy Is One in Which a Player

A trigger strategy is one in which a player

A) cooperates in the current period if the other player cooperated in the previous period, but cheats in the current period only if the other player cheated in the previous period.
B) cheats in the current period if the other player cooperated in the previous period, but cooperates in the current period if the other player cheated in the previous period.
C) cooperates in the current period if the other player has always cooperated, but cheats forever if the other player ever cheats.
D) cheats in the current period if the other player has always cheated, but cooperates forever if the other player has ever cooperated.
E) None of the above.