You can create and edit custom radio button fields for your registration form.
1. Go to your event and click on the 'EDIT' tab.
2. Click on the "EDIT FORM" tab.
3. In the "Add form options" box click on the "Custom Fields" tab.
4. Click on the 'plus' symbol or drop and drag the 'Radio buttons' field onto the registration form.
5. Click on the 'Edit' tool.
6. Type in your radio button question, add options and click 'SAVE'.