Private Sub Form_Click()
  Dim I As Integer, j As Integer
  Dim c As Integer
  c = 0
  For I = 1 To 3
    For j = 1 To 2
      c = c + 3
    Next j
  Next I
  Print c
End Sub
程序运行后，单击窗体，在窗体上显示的结果是（    ）。
A、18 B、15
C、12 D、9

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