When Using the Phone,what Should Be Relied on to Convey

When using the phone,what should be relied on to convey confidence and professionalism?

A) The ability to multitask while on the phone
B) The ability to send links to the audience to support information conveyed while conversing
C) The ability to use tone of voice to convey meaning
D) The ability to block out distractions
E) The ability to keep calls short and to the point