The End-Of-Game Problem

The end-of-game problem:

A) Arises in finitely-repeated games with an uncertain end.
B) Occurs when each stage of a finitely-repeated game with a certain end effectively becomes the last stage.
C) Means that trigger strategies are enforceable.
D) Occurs when players make a move in the last stage of a finitely-repeated game that is different from the move made in the first stage of the game.
E) None of the above are correct.