The correct answer to this open question is the following.
Although there are no options attached we can say the following.
It seems that ypur question is incomplete.
However, trying to help you we can say the following.
In this sentence: "the people in attendance cheered when their team scored the winning goal." Is this an action or act or the state of the mass reaction of mass conduct?
We can say it is a combination of both. It is an action because most people that are considered "fans" of that team, have feelings for the team, like the sport, and cheer when the team scores and wins. They feel good when the team wins because they respect what the team represents.
On the other hand, we can say that it could be the reaction to mass conduct because if people are in a stadium -for instance- they react and follow instinctively what the other people say and do. That is why people in the bleachers scream, shout, cheer, and behave in strange ways they normally do not do.
