It's B because she has a kind and a cruel personality.
Answer: Their
Explanation:
Their = belonging to or associated with the people or things previously mentioned or easily identified.
The author of the text that contains this quote appeals to the reader's sense of logic by quoting an authority/expert on the matter. Taking into consideration that expert's opinions, in argument, are as close to a fact as you can get without actually using a fact, this shows us how your best answer here is option B.
The correct answer is B. While someone else is eating or opening a window or just walking dully along.
Suffering, in Auden's (and old masters') view, is not a drastic case of the human condition. Auden doesn't single it out to depict it in its tragic magnificence. He puts it in the context of ordinary lives of people who mind their own business. It happens in circumstances that are most trivial for those other people. It seems that everyone is either ignorant or indifferent to another person's suffering.