单项选择题

你正在开发一个访问文件系统的程序集。需要写一个代码段当如果现有文件权限禁止使用加载程序集时来配置CLR()

A.[FileIOPermission(SecurityAction.RequestOptional,AllLocalFiles = FileIOPermissionAccess.Read)]
B.[FileIOPermission(SecurityAction.RequestMinimum, AllFiles = FileIOPermissionAccess.Read)]
C.[FileIOPermission(SecurityAction.RequestRefuse, AllFiles = FileIOPermissionAccess.Read)]
D.[FileIOPermission(SecurityAction.RequestOptional, AllFiles = FileIOPermissionAccess.Read)]