在窗体中有命令按Command1和文本框Text1,按的事件代码如下: Public x As Integer Private Sub Command1_Click() x = 10 Call s1 Call s2 MsgBox x End Sub Private Sub s1() x = x + 20 End Sub Private Sub s2() Dim x As Integer x = x + 20 End Sub 运行窗体后,单击命令按,消息框的输出结果是( )。 A. 30.0 B. 10.0 C. 40.0 D. 50.0