I am confused on the question? Do you mind elaborating on what exactly you seek help in?
Answer:
the answer is probably is b
Well, the whole novel is basically told through these letters, so they are used to advance the plot an offer some sense of authenticity to an implausible story. Plus, it is a way for them to express their own feelings and thoughts about the whole thing.
A. Most commonly they order retractions to correct mistakes like plagiarism
