In business communication, which of these is the most formal way to address a superior in writing?

The most formal way to address a superior in writing is to use "Dear [Title] [Last Name]." This salutation is appropriate for formal business communications, such as emails, letters, or any documents where a professional tone is necessary. It demonstrates respect and acknowledges the hierarchical structure within the workplace. Starting with "Dear" followed by their title (such as Mr., Ms., Dr., etc.) and last name is a traditional and accepted format in professional correspondence, ensuring a level of decorum that is expected when communicating with someone in a superior position.

In contrast, the other options employ a more casual tone that would not be suitable in formal business contexts. For example, greetings such as "Hey" or "What's up" diminish the professionalism of the correspondence, while "Greetings [Name]" is still informal and lacks the specific acknowledgment that comes with using titles. These alternatives may be more appropriate among peers or in less formal settings but fall short when it comes to addressing superiors in a business environment.