Private Sub Workbook_Open()
Application.ScreenUpdating = 0
Worksheets("X").Visible = 0: Worksheets("Y").Visible = 0: Worksheets("Z").Visible = 0
Select Case Right$([C17], 1)
Case "X": Worksheets("X").Visible = -1
Case "Y": Worksheets("Y").Visible = -1
Case "Z": Worksheets("Z").Visible = -1
End Select
End Sub