With Regards to the Public Goods Game Without Punishments, Higher

With regards to the public goods game without punishments, higher efficiency implies:

A) Higher contributions to the public account and therefore, higher earnings.
B) Higher contributions to the private account.
C) Higher earnings without subtracting any of the costs incurred in punishing others or the costs of being punished.
D) Higher earnings after subtracting any of the costs incurred in punishing others or the costs of being punished.