In the Study by Brechner (1977)of a Tragedy of the Commons

In the study by Brechner (1977) of a tragedy of the commons dilemma in the laboratory,under what circumstances were participants most able to use the resource effectively?

A) when they were competing against one another
B) when they worked in teams against one another
C) when they were able to communicate with each other
D) when they did not place high value on the outcome