下列程序的执行结果为( )。Private Sub Command1_Click()Dim s1 As String,s2 As StringS1;= abcdef Call Invert(s1,s2)Print s2End SubPrivate Sub Invert (ByVal xstr As String,ystr As String)Dim tempstr As Stringi=Len(xstr)Do While i>=1tempstr=tempstr+Mid(xstr,i,1)i=i-1Loopystr=tempstrEnd Sub
A.fedcba
B.abcdef
C.afbecd
D.defabc