Which phrase best describes a folder in Outlook 2016?
a system for creating messages
an organizational container
a place to create contacts
an itemized calendar of events

The phrase that describes the best folders in outlook 2016 is:

An organizational container.

Explanation:

The reasons behind this answer are that in the first place the folder allows the user to group emails, contacts, tasks, or even a calendar. So, because this is not only for emails or files. It is an object that can group several types of things and create a new category. Instead of only applying for certain objects. Thus, it is an organizational container. Because the first the third, and the fourth option describe objects that can only group-specific objects instead of all of them. There is no flexibility in the rest of the answers.