About Option (RadioButton) Button components
Groups of Option buttons (in the user interface called RadioButtons) are used to select one option from a set of mutually exclusive options. Each button represents one option. When an option is selected, any previously selected button is automatically cleared.
Each member of a group of radio buttons should have the same data binding. You can specify the value represented by a selected button by setting the Radio Button Selected Value property for the component. The value you specify is the value that is assigned to the data binding when the user selects the option button.
When tabbing through a form, pressing TAB moves to the first radio button in a group. Within the group, you can press the UP ARROW key and the DOWN ARROW key to move between radio buttons. Pressing TAB within the group moves to the next component following the group of radio buttons.
To support this standard Windows behavior, the Group property of the first member (in tab sequence) of a group of option buttons should be set to True.