Final answer:
In the context of a CMS like Sitecore, the Sitecore.Data.Fields.MultilistField class is used to retrieve the contents of a Treelist field. This class allows access and manipulation of the selected items in the Treelist.
Step-by-step explanation:
The class you would use to retrieve the contents of a Treelist field largely depends on the context in which you're working. If you're dealing with a content management system (CMS) like Sitecore, you might use API methods provided by the CMS. For instance, in Sitecore, you can use the Sitecore.Data.Fields.MultilistField class to retrieve and manipulate the data from a Treelist field. This class offers methods to access the items selected in the Treelist field.
If you're working in a different context, you may need a different class or method suited to that particular environment or programming language. Regardless of the system, the specific class would provide a means to access each item in the Treelist and potential methods for iteration or manipulation of those items.