（24）在窗体上画1个名为Text1的文本框和1个名为Labe11的标签，再画4个名为Op1的单选按钮控件数组，

其Index属性按季度顺序为0~3，如图1所示。在文件Sales.txt中按月份顺序存有某年12个月的销售额，并把相应的文字显示在标签上。如图2所示是单击“第二季度”单选按钮所产生的结果。请选择可在空白处填写的合适语句Option Base 1 Dim sales(12)As Load Private Sub For_Load() Open"c:\sales.txt"For Input As#1 For k=1 To 12 Input#1,sales(k) Next Close#1 End Sub Private Sub_________(Index As Integer) Dim sum As Long,k As Integer,month As Integer sum=0 Month=Index*________ For k=1 To 3 month=month+1 sum=sum+sales(month) Next k Label1.Caption=__________.Caption&"销售总额：" Text1=sum End Sub A.Op1_Click 3 Op1(Index) B.Op1_Click 0 Option1(Index) C.Option1_Click 1 Op1(Index) D.Option1_Click 2 Option1(Index)