单项选择题

下列程序的执行结果为( )。   Ptivate Sub Commandl_Click()     Dim FirStr As String     FirStr="abcdef"     Print Pct (FirStr)   End Sub   Private Function Pct(xStr As String)As String     Dim tempStr As String,strLen As Integer     tempStr=""     strLen=Len(xStr)     i=1     Do While i<=Len(xStr)-3       tempStr=tempStr + Mid(xStr,i,l) + Mid(xStr,strLen - i+i ,1)       i=i + 1     Loop     Pct=tempStr   End FunCtion

A.abcdef
B.afbecd
C.fedcba
D.defabc