—When can I go out to play football, Mum? 

—Finish your homework first, otherwise I won't let you ________.[ ]

A. to go out

B. go out

C. going out

D. will go out

阅读下面的程序：
Private Sub Command1_Click()
For i=1 To 3
For j=1 To i
For k=j To 3
x=x+1
Next k
Next j
Next i
Print x
End Sub
程序运行后，单击命令按钮，窗体上输出的结果是

A．3

B．9

C．14

D．21