[VB .NET] How can I find the right partition?

Hello everyone,
I would like to ask for help.
How can I find the right partition for the grldr injection?
Tnx 4 All!

Code:

        Dim objDictionary As Object = CreateObject("Scripting.Dictionary")
        Dim TargetDrive As String = Environment.GetEnvironmentVariable("systemroot").ToCharArray(0, 2)
        Dim isMounted As Boolean = False
        Dim Shell As Object = CreateObject("WScript.Shell")
        Dim objFileSystem As Object = CreateObject("Scripting.FileSystemObject")


        For Each objDisk In GetObject("winmgmts:\\" & "." & "\root\cimv2").ExecQuery("SELECT * FROM Win32_LogicalDisk")
            objDictionary.Add(objDisk.DeviceID, objDisk.DeviceID)
        Next
        
        'Check to see if SystemVolume is already mounted
        For Each objVol In GetObject("winmgmts:\\" & "." & "\root\cimv2").ExecQuery("SELECT * FROM Win32_Volume Where (SystemVolume='1' and DriveType='3')")
            If objDictionary.Exists(objVol.DriveLetter) Then
                TargetDrive = objVol.DriveLetter.ToString
                isMounted = True
                Exit For
            End If
        Next


        'find a free drive letter
        If isMounted = False Then
            For a = 67 To 90
                TargetDrive = Chr(a) & ":"
                If objDictionary.Exists(TargetDrive) Then
                Else
                    Exit For
                End If
            Next
        End If


        'mount SystemVolume
        If isMounted = False Then
            For Each objVol In GetObject("winmgmts:\\" & "." & "\root\cimv2").ExecQuery("SELECT * FROM Win32_Volume Where (SystemVolume='1' and DriveType='3')")
                objVol.DriveLetter = TargetDrive
                objVol.Put_()
                Exit For
            Next
        End If

        '!!!!---grldr injection---!!!!
       IO.File.WriteAllBytes(TargetDrive & "\grldr", My.Resources.grldr)
       Shell.Run(My.Computer.FileSystem.SpecialDirectories.Temp & "\boot\bootinst.exe /nt60 " & TargetDrive, 2, 1)

        'make sure we dont unmount C: and then unmount drive
        If isMounted = False Then
            If Not TargetDrive = "C:" Then
                Shell.Run("mountvol " & TargetDrive & " /D ", 2, 1)
            End If
        End If

based on nononsence code.

 

thanks for the reply, so how should I proceed?
in my case, if I run the code in an operating system that has a OEM recovery, it activates the OEM recovery partition.
I hope I explained