单项选择题 You use Microsoft .NET Framework 4 to create a Windows Forms application. You write the following code segment. (Line numbers are included for reference only.) You need to ensure that the first time each user opens the application, a text field displays the following message: "Please enter your setting." Which code segment should you insert at line 03? （）

单项选择题 You use Microsoft .NET Framework 4 to create a Windows Forms client application. You write the following code segment. The application contains a form of type Form1 that contains a FormSettings object named frmSettings1. You need to maintain the users form size preference each time the user executes the application. Which code segment should you use? （）

单项选择题 You upgrade a Windows Forms application to Microsoft .NET Framework 4. The application was developed by using a previous version of the .NET Framework. The application uses the Code Access Security (CAS) policy for file access. When the application is executed, you receive the following exception: "NotSupportedException: This method uses CAS policy, which has been obsoleted by the .NET Framework." You need to resolve the error. What should you do?（）