OptionButton Object [Access 2003 VBA Language Reference]
An option button on a form or report is a stand-alone control used to display a Yes/No value from an underlying record source
Note This control should not be confused with the Dynamic HTML option button control used on a data access page. For information about an option button control on a data access page, see Option Button Control (Data Access Pages).
Using the OptionButton object
When you select or clear an option button that's bound to a Yes/No field, Microsoft Access displays the value in the underlying table according to the field's Format property (Yes/No, True/False, or On/Off).
You can also use option buttons in an option group to display values to choose from.
It's also possible to use an unbound option button in a custom dialog box to accept user input.