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 n=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)
