simple userform code

I have asimple userform which consists of 2 option buttons (1 and 2) and one combo box (with choice of a b c and d). What i want to do is have user select one or the other option buttons (1 or 2) and the combobox display a and b if option button 1 selected or c and d if option button 2 selected.
Then user selects a or b or c or d and the result to be saved as an attribute for a block insertion. Can anyone supply mewith some code to do this

 

In the click event handler for each option button, clear the contents of
the combobox and refill it with the appropriate values.

 

how do i do that. i am just a new programmer

 

this is what i have at present


Private Sub OptionButton1_Click()
If OptionButton1 = True Then
Cbofirstend.AddItem "a"
Cbofirstend.AddItem "b"
Cbofirstend.ListIndex = 1
End If
If OptionButton2 = True Then
'clear combobox'

Cbofirstend.AddItem "c"
Cbofirstend.AddItem "d"
Cbofirstend.ListIndex = 1
End If
End Sub

 

Almost there. Separate the two blocks of code; the top section in
OptionButton1_Click, the bootm section in OptionButton2_Click.

Next, be sure to clear the Combobox before you start adding items to it.

 

Private Sub OptionButton1_Click()
With ComboBox1
.Clear
.AddItem "A"
.AddItem "B"
.ListIndex = 0
End With
End Sub

Private Sub OptionButton2_Click()
With ComboBox1
.Clear
.AddItem "C"
.AddItem "D"
.ListIndex = 0
End With
End Sub

No need for any "if then" construct