It is a primary source, because it's coming from the account of Rose Lipszyc, the speaker, who was born in Lublin, Poland in 1929, and was the only surviving member of her family. She found out she was being taken away after her family way ordered to congregate in a small town. A knock on a door later, and her family was divided. The music proved to be very effective in relaying a sad tone, as well as the imagery the speaker used.
The answer b states that "from then on" meaning her behavior has changed toward her brother and the passage states how she has been putting a little extra thought into how she interacts with her brother.
