The Main Challenge in Writing a Good Thank-You Note Is

The main challenge in writing a good thank-you note is ________.

A) including specific details about the act for which you are expressing gratitude
B) writing legibly so that your reader can understand the content of your message
C) coming up with a message generic enough that it could be used for anyone by just changing names
D) making an apology sound sincere when you are just going through the motions
E) keeping the details to a minimum so that your message isn't too lengthy