单项选择题

设窗体上有一个文本框Text1和一个命令按钮Command1,并有以下事件过程:
Private Sub Command1_Click()
Dim s As String, ch As String
s=""
For k=1 To Len(Text1)
ch=Mid(Text1,k,1)
s=ch+s
Next k
Text1.Text=s
End Sub
程序执行时,在文本框中输入Basic,然后单击命令按钮,则Text1中显示的是

A.Basic
B.cisaB
C.BASIC
D.CISAB