单项选择题

下列程序 Private Sub Command1_Click( ) x = "abcd" y = "1234"  For i = 1 To 4    z = z + Mid(x, i, 1)+ Left(y, 1) Next i  Print zEnd Sub 程序运行后,单击命令按钮,则窗体上显示的内容是()。

A.abcd1234
B.a1b2c3d4
C.a1b1c1d1
D.1234abcd