Which of the Following Must Managers Do as Senders of Messages

Which of the following must managers do as senders of messages?

A) They must filter the information before sending.
B) They must encode messages in symbols that only they understand to maintain confidentiality.
C) They must select a medium which they are comfortable using irrespective of its appropriateness for the message.
D) They must select a medium that the receiver does not monitor.
E) They must ensure that a feedback mechanism is built into messages.