I believe it is C-available by prescription but I am not too sure. Cocaine is used by physicians and for other medical purposes so it could be prescribed.
They were in a complex relationship
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,
__"