单项选择题

下列程序的执行结果为( )。   Private Sub Commandl_Click()     Dim s1 As String ,s2 As String     s1= "abcd"     Call Transfer(sl,s2)     Print s2   End Sub   Private Sub Transfer (ByVal xstr As String,ystr As String)     Dim tempstr As String     ystr=tempstr   End Sub

A.1
B.2
C.随机输出1或2
D.程序有错