In Terms of Phone Use,good Etiquette Suggests Which of the Following

In terms of phone use,good etiquette suggests which of the following as being most important?

A) Speaking softly so others in the work space are not disturbed
B) Don't waste time identifying yourself-it is no longer necessary with caller I.D.
C) Allow calls to go to voicemail whenever possible to keep a record of calls
D) Identify yourself when answering the phone before asking how you can be of help
E) Using voice mail instead of other means for messaging