A run-on sentence is a sentence having two independent clauses with improper punctuation and without conjunctions. The correct answer is option b. It is difficult to understand a run-on sentence because you cannot identify where to pause or stop and that the sentence does not have conjunctions which would help in the transition of clauses.
I would say C. “was”. It’s definitely not “am”, because that just sounds completely wrong. It’s not “are” because that sounds a bit wrong, too. It can’t be “were” because it’s only referring to one group, not many groups. The only answer it could be is C.
It sets the scene of pre-revolutionary France and demonstrates dickens’ sympathy toward the people of France at this time. The quote is important because it still shows the humanity of the peasants before it is ripped away from them by the hatred and violence brought on by the revolution.