Which of the following is TRUE about the use of email as a mode of business communication?

$1$ point

A$)$ Email is usually the best choice for brief online conversations.

B$)$ Email is not suitable for private, short$-$ to medium$-$length messages; IM or Twitter are more effective for this purpose.

C$)$ You need to join a special online group or be friended by a group member in order to communicate with someone through email.

D$)$ Email allows senders to compose substantial messages in private and on their own schedule, and it allows recipients to read those messages at their leisure.