What is the best user interface widget for ternary data?

In a form design wizard people can define mark fields, and then state how important there are. Some fields will always be in the form (for other purposes). However for one such field a person can state 3 "levels" of how they work:

• Required (field is required and cannot be left empty by end user)
• Optional (field is optional/can be left blank)
• Disabled (field cannot be edited by user/will always be blank).

Since each of those options is mutually exclusive using multiple checkboxes/sliders is not the correct way.

An option is to use 3 radio buttons - however this uses a lot of "room" for such a simple definition.

Is there a better tool? Where I can easily show the ternary status and have easy feedback (also on mobile)?