Which statement on the equilibrium in the once repeated PD game iscorrect?

1. Playing (D, D) in the first round can be the outcome of a dominant strategy equilibrium.
2. Playing (D, D) in the second round can be the outcome of a dominant strategy equilibrium.
3. Playing (D, D) in the first round can be the outcome of a subgame perfect equilibrium.
4. Playing (C, C) in the first round can be the outcome of a Nash equilibrium