Answer:
One advantage of communicating via e-mail is that it is C) a secure and private communication.
Explanation:
Now a days communicating via e-mail is a secure and private way to communicate. It is often necessary for work, everyone now a days is using this tool to send messages to one and other and now that it would be private and also effective. It is secure because you now it won´t get lost or missplaced, it is certain tan the e mail you sent would be most likely delivered, and also you can be certain that no one but the owner of the e mail adress would read it.
It is no only used for working reasons, it can also be a way to contact someone for personal reasons, to confirm appointments, to even send medical results. Now a days even laboratory results are sent by mail, that is how private and secure communicating via e mail is.