It means that you are aware and are paying attention.
One of the rules in proper parenthetical citation says that when the author of the source is given, it should be written using the author's name and page number. But if without the author's name, the title of the book or article is used as a subsitute, following the page number. Since the name of the author has been mentioned, the correct answer would be, letter A. (Simpson 91)
My personal recommendations would be to
A ) Make the subject shorter, like "Reason for Absence" or "My Absence"
B ) Make the email more formal. (You don't have to copy my recommendation word for word but if you want to or use it for reference that works):
"Good Morning/Afternoon/Evening Mrs. __,
I hole you're have a lovely morning/afternoon/evening. Today I was absent and I apologize for the inconvenience. The class meeting didn't appear on my canvas courses and I couldn't find a zoom link. If there's anywhere I can find either one for the future please let me know and again I'm sorry for the inconvenience.
Sincerely,
__"
