单项选择题

编写如下事件过程,当程序运行后,为了在窗体上输出BBBB,应执行的操作为 ______ 。
Private Sub Form_MouseDown(Button As Integer,_
Shift As Integer,X As Single,Y As Single)
If Shift = 6 And Button = 2 Then
Print "BBBB"
EndIf
End Sub

A.同时按下Shift 键和鼠标左键
B.同时按下Shift键和鼠标右键
C.同时按下Ctrl、Alt键和鼠标左键
D.同时按下Ctrl, Alt键和鼠标右键