applying select case function to selectable options in listbox

I have a listbox with multiple options to choose from on sheet1. On sheet2 I have the actual options that come up when selecting from the list box. the list box works in conjunction with the combobox to generate graphs. Certain options in the combobox only relate to particular options in the listbox. How do I write a select case function that will basically say, if you choose this one from the combobox, then only these options are available in the list box, and if you choose this other one in the combobox then only these other options are available in the listbox, and so on?

Here is the code for the combobox in question:

Sub Populate_Combobox_Worksheet()




    'This line of code locks the boxes in place and prevents them from resizing
    ThisWorkbook.Worksheets("sheet1").Shapes("CommandButton1").Placement = xlFreeFloating

    'The Excel workbook and worksheets that contain the data, as well as the range placed on that data
    Dim wbBook As Workbook
    Dim wsSheet As Worksheet
    Dim rnData As Range

    'Variant to contain the data to be placed in the combo box.
    Dim vaData As Variant

    'Initialize the Excel objects
    Set wbBook = ThisWorkbook
    Set wsSheet = wbBook.Worksheets("Sheet3")

    'Set the range equal to the data, and then (temporarily) copy the unique values of that data to the L column.
    With wsSheet
        Set rnData = wsSheet.Range(wsSheet.Range("A1"), wsSheet.Range("A100").End(xlUp))
        rnData.AdvancedFilter Action:=xlFilterCopy, _
                          CopyToRange:=wsSheet.Range("L1"), _
                          Unique:=True
        'store the unique values in vaData
        vaData = wsSheet.Range(wsSheet.Range("L1"), wsSheet.Range("L100").End(xlUp)).Value
        'clean up the contents of the temporary data storage
        wsSheet.Range(wsSheet.Range("L1"), wsSheet.Range("L100").End(xlUp)).ClearContents
    End With

    'display the unique values in vaData in the combo box already in existence on the worksheet.
    With ThisWorkbook.Worksheets("sheet1").OLEObjects("ComboBox1").Object
        .Clear
        .List = vaData
        .ListIndex = -1
        
   
     
        
    End With

End Sub

And here is the code for the listbox in question:

Sub Populate_ListBox_Worksheet2()

    'This line of code locks the boxes in place and prevents them from resizing
    ThisWorkbook.Worksheets("sheet1").Shapes("CommandButton1").Placement = xlFreeFloating


    'The Excel workbook and worksheets that contain the data, as well as the range placed on that data
    Dim wbBook As Workbook
    Dim wsSheet As Worksheet
    Dim rnData As Range

    'Variant to contain the data to be placed in the combo box.
    Dim vaData As Variant

    'Initialize the Excel objects
    Set wbBook = ThisWorkbook
    Set wsSheet = wbBook.Worksheets("Sheet3")

    'Set the range equal to the data, and then (temporarily) copy the unique values of that data to the L column.
    With wsSheet
        Set rnData = .Range(.Range("C1"), .Range("C100").End(xlUp))
        rnData.AdvancedFilter Action:=xlFilterCopy, _
                          CopyToRange:=.Range("L1"), _
                          Unique:=True
        'store the unique values in vaData
        vaData = .Range(.Range("L1"), .Range("L100").End(xlUp)).Value
        'clean up the contents of the temporary data storage
        .Range(.Range("L1"), .Range("L100").End(xlUp)).ClearContents
    End With

    'display the unique values in vaData in the combo box already in existence on the worksheet.
    With ThisWorkbook.Worksheets("sheet1").OLEObjects("ListBox1").Object
        .Clear
        .List = vaData
        .ListIndex = -1
    End With

End Sub

Awesome. Thanks so much, this is really helpful!

OK, I tried it with and without, and still getting the same error of "object required". So frustrating. I dont understand what it is about "ListBox1.clear" thats tripping up the program, or what "object" that it requires. Anything helps. Thanks

@Everstrivin

Thanks a bunch for your recommendation. One question though. You suggested "listBox1.Items.Clear();". Is the ";" part of the line of code as well?

Also, thanks for suggesting how I can check code!