You use Microsoft .NET Framework 4 to create a Windows Presentation Foundation (WPF) application. You add a DataGrid named gridContacts that is data-bound to a collection of Contacts. Each item has the ContactName and Phone properties. The DataGrid contains a column named ContactNameColumn that is bound to ContactName. You write the following code fragment. You need to ensure that the application meets the following requirements: Phone number is shown as a row detail when the row is selected. Only ContactName can be edited. What should you do?（）

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