Why Was the Collective Action Problem of Ozone Depletion Easier

Why was the collective action problem of ozone depletion easier to overcome than the collective action problem of global warming?

A) The reward to defect on global warming is higher.
B) Global warming is caused by individual activity,while ozone depletion is generally caused by states.
C) There were a fewer number of actors involved in dealing with ozone depletion.
D) The fight to stop global warming occurred within a privileged group.
E) TANs have failed to rally for global warming.