在窗体上画一个名为Command1的命令按钮，其Command1_Click事件过程如下： Sub Command1_Click() Dim student As studtype Dim record_no As Integer record_no=1 With student .ino=12 .strname="smith" .strsex="男" .smark=89 End With ______ Put # 1，record_no，student Close # 1 End Sub 要求在c:\的随机文件student.dat写入一条记录。应在程序中空行处填入以下哪条语句使该功能完整
A．Open"c:\student.dat"For Input As # 1 len=len(student) B．Open"c:\student.dat"For random As # 1 len=len(student) C．Open"c:\student.dat"For Output As # 1 len=len(student) D．Open"c:\student.dat"For Append As # 1 len=len(student)