In most cases, there are usually more than one option button to choose from. As to say for example, there are three options and you will select one of the three. Again, usually, these option buttons are placed into a Frame control so as to reduce the over head required to determine which option is selected. If this is the case, then to set any one option button within the frame group to true, you would use the following code:
Me.Frame1.Value = 2
Where: Frame1 is the Frame control that has grouped three option buttons. 2 is the Index number of the option button within the Frame group. In this case, the second option button.
The code line above sets the second Option button to TRUE and all others to false.
The code line below sets the third Option button to TRUE and all others to false.