单项选择题 You are developing a Windows Presentation Foundation (WPF) application that displays opportunities from List<T.. class named Lead. The Lead class contains the properties Title and Revenue. You add a DataGrid control named dgQualifiedLeads to the MainWindow.xaml file. You set the ItemsSource property to Leads as follows. You need to ensure that CollectionViewSource is used to filter the list to display only Lead objects with revenue ... What should you do ?（）

单项选择题 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？（）

单项选择题 You need to ensure that phone numbers are displayed in the following format : (###) ### - ### Which markup segment should you use ?（）