问题：

[单选]

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 Sub _ 

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 - 24 - Test Information Co., Ltd. All rights reserved. CustomValidator1_ServerValidate(ByVal source As Object, _ 
ByVal args As ServerValidateEventArgs) 
Dim dt As DateTime = _ 
IIf([String].IsNullOrEmpty(args.Value), _ 
DateTime.Now, Convert.ToDateTime(args.Value)) 
args.IsValid = (DateTime.Now - dt).Days < 10 
End Sub 
You need to validate the value of TextBox1. 
Which code fragment should you add to the Web page? （）

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