Subgame perfection is a refinement of Nash Equilibrium that requires
Select one:
a. perfect and skilled play by all players
b. credibility/rationality at every point/path in the game, regardless of whether those points/paths are actually part of the Nash equilibrium
c. focalness in equilibrium
d. firms do not cheat on their output agreements
e. credibility/rationality only along the equilibrium path
