You are creating a Windows Forms application by using the .NET Framework 3.5.  You use LINQ expressions to read a list of customers from the following XML file.

You need to obtain a list of names of customers who are 21 years of age or older.  
Which code segment should you use？（）

You are creating a Windows Forms application by using the .NET Framework 3.5.The application stores a list of part numbers in an integer based array as shown in the following code segment （Line numbers are included for reference only）

You need to use a LINQ to Objects query to perform the following tasks： - Obtain a list of duplicate part numbers：
（1）Order the list by part numbers  
（2）Provide the part numbers and the total count of part numbers in the results   
Which code segment should you insert？（）