You are developing WPF application for managing student information... btnSort and a DataGrid control named dgStudents on the design surface of the MainWindow.xaml properties : FirstName and LastName. You create the following code segment in the constructor of...

The DataGrid control displays the list of students unsorted.
You need to ensure that the list of students is sorted by last name.
Which code segment should you add to the click event handler of the Button control？（）