Why Does a Nash Equilibrium Represent a Plausible Outcome for a Game

Why does a Nash equilibrium represent a plausible outcome for a game?

A) If Party A chooses first,the outcome is the same as its expectation regardless of B's choice
B) If Party B chooses first,the outcome is the same as its expectation regardless of A's choice
C) Regardless of which party chooses first,if they both expect the other to choose a its Nash equilibrium,then both parties expectations will equal the outcome.
D) Neither party needs to make a choice,the market forces an agreeable equilibrium outcome
E) None of the above are correct