C. To develop his claim that indifference may be easy, but it is wrong
The speech is titled "The Perils of Indifference". Something that is in peril is in danger. This speech is all about the dangers of being indifferent. From this idea we can discern that Wiesel sees being indifferent as dangerous. In the excerpt he says that "it is so much easier to look away from victims." He then goes on to say by being indifferent, the people we are indifferent towards become meaningless and an abstraction. Here he showing how it is wrong to be indifferent.
The other options are simply incorrect. He doesn't say here that people must be polite. He is not talking about students in school and he isn't talking about interrupting someone who is working. He uses his examples to show how being indifferent is easier than caring about others.