The Folk theorem suggests that

a.

the one-shot Nash equilibrium will be the only sub-game perfect equilibrium

b.

in an infinitely repeated game, any equilibrium can be supported as a sub-game perfect equilibrium regardless of the discount factor

c.

payoffs superior to the one-shot game can be supported as sub-game perfect equilibria in an infinite game if the discount factor is close to one

d.

in a finitely repeated game, any equilibrium can be supported as a sub-game perfect equilibrium regardless of the discount factor