B. to set a precedent means to do something that's never been done before
The minority has a distinct identity based on physical or cultural traits, and minority experiences subordination
This is an example of encounter structuring.
Encounter structuring refers to a situation in which a person will try to modify what they say in order to avoid a conflict. In this case, Sarah will refrain from talking about politics with her husband's family because they have different affiliations and are bound to have a fight, which happens every time she visits.