Which event of the GridView class occurs when the Edit button of a row is clicked， but before the GridView control enters edit mode？（）

You work as an ASP.NET Web Application Developer for SomeCompany. The company uses Visual Studio .NET 2010 as its application development platform.  You create an ASP.NET Web application using .NET Framework 4.0. The ASP.NET application is used to track employee performance. It uses Microsoft Windows authentication. Employees are members of a group named Employees.  Managers are members of a group named Managers.  The root folder of the application is named Details. The Details folder displays information about employees„ performance.  The Details folder has a subfolder named MoreDetails. You need to ensure that employees and managers can access pages stored in the Details folder. However， only managers can access pages stored in the MoreDetails folder.   
You make the following entries in the Web.config file in the Details folder.
You make the following entries in the Web.config file in the MoreDetails folder.
When managers try to access pages stored in the MoreDetails folder， they receive the following error message："An error occurred during the processing of a configuration file required to service this request." You must ensure that managers are able to access pages stored in the MoreDetails folder. What will you do to accomplish this？（）