"Sandy, was unhappy with her grades," is not punctuated correctly. There is no need for the comma.
Memoirs are written in order for the author of it to: Reflect back on a time in his or her life. It is like a story that is a complete flashback of events. Hope that helps.
Answer: A
Explanation: Couldn't be B or C
B it shouldn't really matter about the length.
C is opinionated.