Select the Best of These Closing Sentences for a Message

Multiple Choice

Select the best of these closing sentences for a message refusing to participate as a speaker at an event.

A) "I wish the event turns out to be a great success."
B) "I regret that I must refuse."
C) "I sincerely hope that you understand why I made this decision."
D) "Perhaps next time I will not have to refuse."
E) "Please forgive me this time."