Target .NET Framework Version, also sets the target Visual Studio version.
Select Version 4.5 for Visual Studio 2012/2013/2015, Version 4.0 for Visual Studio 2010, Version 3.5 for Visual Studio 2008 and Version 2.0 for Visual Studio 2005, otherwise with Version 1.1, Visual Studio 2003 is targeted.
Note: while regeneration to the same ProjectPath folder is usually supported, you cannot change the FrameworkVersion for an existing target ProjectPath folder
Note that if you select Framework 2.0 or higher, you will be provided the option to build the application without the need for opening the Visual Studio solution and building there.
You should not select a Framework version not installed on your computer, or the generation will fail.
If you do not have a copy of Visual Studio, you should select Framework 3.5 and install it if necessary.