You create a Microsoft ASP.NET application by using the Microsoft .NET Framework version 3.5. You add a TextBox control named TextBox1.  You write the following code segment for validation：   protected void CustomValidator1_ServerValidate（object source， ServerValidateEventArgs args） {   DateTime dt = String.IsNullOrEmpty（args.Value） ？ DateTime.Now ： Convert.ToDateTime（args.Value）；   args.IsValid = （DateTime.Now - dt）.Days < 10；   }   You need to validate the value of TextBox1.  Which code fragment should you add to the Web page？ （）

• A、A
• B、B
• C、C
• D、D