Which of the following statements best describes the use of letters, e-mails, and memos in business today?
A、Businesses use memos to deliver positive messages internally and externally, but they use a formal business letter to deliver negative messages.
B、E-mail delivers most internal communication, hard-copy memos deliver most external communication, and letters communicate only legal issues.
C、Despite the popularity of e-mail, in certain situations letters remain the preferred channel of communication for delivering messages outside an organization.
D、Businesses today use e-mail, memos, and letters interchangeably for all audiences, purposes, and messages.