You are delivering your salary and benefits proposals for employees in your department to your supervisor. What is the best communication channel to deliver this confidential information?

C) interoffice memo

Explanation:

Interoffice memorandums (memos) are formal ways of communicating within an organization. They are basically formal letters that must include the recipient (who should receive the memo), the sender, the date and the subject of the memo.

In this case, you are dealing with a very sensitive and confidential subject, salaries and benefits are always sensitive subjects, so you must communicate your proposal in a formal way.