Something about sections

I have this section structure

Section "op1" op1

SectionEnd



Section  /o "op2" op2

SectionEnd



Section /o "op3" op3

SectionEnd



Section /o "op4" op4

SectionEnd

And I have this code:

Function .onSelChange
!insertmacro StartRadioButtons $R5 #op2
!insertmacro RadioButton ${op2}
!insertmacro RadioButton ${op4}
!insertmacro EndRadioButtons
FunctionEnd 

The user can select either op2 or op4...ok, How can I also select op3, if the user selects op3 and de-selected when the user selects op2?