You create a Microsoft ASP.NET application by using the Microsoft .NET Framework version 3.5. The application contains a DataSourceControl named CategoriesDataSource that is bound to a Microsoft SQL Server 2005 table. The CategoryName column is the primary key of the table. You write the following code fragment in a FormView control. （Line numbers are included for reference only.） 01 <tr> 02 <td align="right"><b>Category：</b></td> 03 <td><asp：DropDownList ID="InsertCategoryDropDownList" 04 05 DataSourceID="CategoriesDataSource" 06 DataTextField="CategoryName" 07 DataValueField="CategoryID" 08 RunAt="Server" /> 09 </td> 10 </tr> You need to ensure that the changes made to the CategoryID field can be written to the database. Which code fragment should you insert at line 04？（）
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