You create a Microsoft ASP.NET application by using the Microsoft .NET Framework version 3.5. The application is deployed on a Microsoft IIS 6.0 Web server by using the default ASP.NET version 2.0 application pool and Windows Authentication.  The application contains functionality to upload files to a location on a different server. Users receive an access denied error message when they attempt to submit a file. You need to modify the Web.config file to resolve the error.  Which code fragment should you use？（）

• A、A
• B、B
• C、C
• D、D