Function F(a As Integer)
   Dim b As Integer
   Static c As Integer
   b = b + 2
   c = c + 3
   F = a + b + c
End Function
Private Sub Command1_Click()
   Dim a As Integer
   a = 4
   For i = 1 To 3
    Print F(a);
   Next i
End Sub
程序运行后,单击窗体，在窗体上显示的值是（   ）。
A、9  9  9
B、9  12 15
C、9  14 19
D、9  11 13

---