A radio button is used to select an option, usually from a group of radio buttons. Unlike a check box, only one radio button in a group may be selected at a time. When a radio button is selected, it displays a black center to indicate that it has been selected. Typically, a group of radio buttons would be used to indicate a choice, such as a payment method (for example, cash, check, or credit card).
Because radio buttons always function in sets, if you want multiple sets of radio buttons in a screen, you should draw each set of buttons inside a frame control. When a set of radio buttons is inside a frame, clicking one of the buttons clears the other buttons in the set.