Answer:
C
Step-by-step explanation:
Can't seem to find an answer button, but the answer I would assume is C. There wasn't a place in the text directly referring to the answer, however, judging from how many times the fact the walzer was written as disgraceful and awful, peasants would most likely be the ones to dance the walzer because they wouldn't care about customs like that.
I will tell you that it is definitely not B, and A would most likely be wrong as well because the fact that peasants did not associate with members of the upper class has little to do with why only peasant danced the walzer.