The correct answer to this open question is the following.
Although the question is incomplete because it does not provide a specific reference about the author of the letter or any other reference, we can comment on the following.
A primary source is the piece of information that was written by a character or an individual that lived in the moment of the event, was part of the event, or witnessed the event. This individual could have written a letter, or a document -including a book. Or he/she took a photograph. Or was part of an interview. The secondary source includes information from a third person who was not part of the time or event but has found information through other resources. It is the case of an encyclopedia or researchers/historian books.
7 MILLION PEOPLE.
It is crazy to even imagine that 7 MILLION PEOPLE in this world were lost.
Answer:
Muslim merchants migrated east to the land of Tang, Changan and other Chinese cities, Some merchants returned to their lands but others remained in those lands with the Tang emperor's permission and also allowed them to marry Chinese women. In Islam, Muslim children were also Muslims and the religion in the East rose.
Answer:
I think it's C. Texas recovered more quickly than the rest of the South after the Civil War.
(I'm so sorry if it's wrong)
Hope this Helps!