单击命令按钮时，下列程序代码的执行结果为______。

单击命令按钮时，下列程序代码的执行结果为______。  Private Sub Button1_Click(…) Handles Button1.Click  Dim a As Integer, b As Integer, c As Integer  A = 2 : b = 3 : c = 4  MsgBox(SecProc(c, b, a))  End Sub  Private Function FirProc(ByVal x As Integer, ByVal y As Integer, ByVal z As Integer)  FirProc = 2 * x + y + 3 * z  End Function  Private Function SecProc(ByVal x As Integer, ByVal y As Integer, ByVal z As Integer)  SecProc = FirProc(z, x, y) + x  End Function  A）21 B）19 C）17 D）34  

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