There doesn't seem to be any way to:
- query a set of RadioButtons as to which of them is selected
- query a specific RadioButton as to whether it is selected
- select or deselect a specific RadioButton from code
In order to determine which RadioButton in a set is selected, you have to track it in code by responding to the Click event, which is also triggered when the control's value changes by means other than a mouse-click. You also have to know which one is set by default by running the program and examining which radio button displays as selected.