In Which of the Following Negative Situations Would It NOT

In which of the following negative situations would it NOT be appropriate to send an e-mail message to one of your colleagues?

A) You have to tell her that you will be late to the meeting she's called for tomorrow because of a doctor appointment.
B) You are extremely angry because of a message she has just sent you and you want to tell her how wrong she is.
C) You have found you made an error when you gave her some sales figures this morning.
D) You have just found out that the firm has lost a client for whom you have both been preparing materials.
E) All of the above are appropriate.