You create a Microsoft ASP.NET application by using the Microsoft .NET Framework version 3.5. You plan to add a custom parameter in the SqlDataSource control. You write the following code fragment：  
<asp：SqlDataSource ID="SqlDataSource1" runat="server"  
InsertCommand="INSERT INTO [Employee] （[Field1]， [Field2]， [PostedDate]）   
VALUES （@Field1， @Field2， @PostedDate）"> 
<InsertParameters>  
<asp：Parameter Name="Field1" />  
<asp：Parameter Name="Field2" />  
<custom：DayParameter Name="PostedDate" /> 
</InsertParameters>  
</asp：SqlDataSource>   
You write the following code segment to create a custom parameter class：  
public class DayParameter ： Parameter { }
You need to ensure that the custom parameter returns the current date and time. Which code segment should you add to the DayParameter class？ （）

A.A
B.B
C.C
D.D