执行下列程序后，鼠标单击窗体，输出结果为
Private Sub Form_Click()
　　Print"Click"：
End Sub
Private Sub Form_MouseDown(Button As Integer，Shift_As Integer，X As Single，Y As Single)
　　Print"Donw"
End Sub
Private Sub Form_MouseUp(Button As Integer，Shift_As Integer，X As Single，Y As Single)
　　Print"Up"
End Sub

A．DownUpClick

B．CfickDownUp

C．DownClickUp

D．UpDownClick