How to get open folders list using C#?

To Open a particular folder in Explorer, just:

System.Diagnostics.Process.Start(@"explorer.exe", @"C:\Windows");

In fact, as Explorer is the asscoaited handler for folder, that could be written as:

System.Diagnostics.Process.Start(@"C:\Windows");

or

 string path="D:\\Test";

 System.Diagnostics.Process.Start("explorer.exe", path);