The professor responded in this way, as he felt disrespected by Westover's question and did not like the situation.
We can arrive at this answer because:
Westover didn't really know what the holocaust was, as she was raised with no access to any information, so she asked the meaning of the word, but no one in the class knew about it.
You can find out more about the holocaust here:
https://brainly.com/question/308446