Hi Kimberly,
You can create a custom field for Region and add that in the Survey as a required field.
To create a Custom Contact Field: Here is the article link (https://app.cvent.com/Subscribers/Account/default.aspx?page=BE132BFF-ADD3-41F2-BCC9-4DBCE592E47E&targetPath=apex/CommunityArticle?id=000002703).To add that to a Survey, you can go to:Design Survey > Questions > Edit Contact Profile > Add the Region Field.You can make it required on the next step.
Hope this helps.RegardsAnkita Gupta