登录窗体如图所示。单击"登录"按钮，当用户名及密码正确时则会弹出窗口显示"OK"信息。
下列过程不能完成此功能的是

A．Private Sub cmdOK_Click() If txtUser.Value = "zhangs" And txtPW.Value = "123" Then MsgBox "OK" End if End Sub
B．Private Sub cmdOK_Click() If txtUser.Value = "zhangs" Then If txtPW.Value = "123" Then MsgBox "OK" End if End if End Sub
C．Private Sub cmdOK_Click() If txtUser.Value = "zhangs" Then If txtPW.Value = "123" Then MsgBox "OK" End if End Sub
D．Private Sub cmdOK_Click() If txtUser.Value = "zhangs" and txtPW.Value = "123" Then MsgBox "OK" End If End Sub