My DD received a letter of assurance from the naval academy about a month ago. She is in all advanced courses, and her grades to be a bit below what they used to be. Last year, she was in 4 advanced classes, and got all A's. This year, she is in 7 advanced classes and is getting A's, B's. Could this slight drop in grades despite the step up in the rigor of the courses "cancel out" her letter of assurance, even if she gets a nomination? Thanks in advance.