Which of the following is NOT considered a fixture in real estate?

A fixture in real estate is typically defined as an item that was once personal property but has been permanently attached to the property in such a way that it becomes part of the real estate. To determine whether an item is a fixture, several factors are considered, including the method of attachment, the intention of the parties involved, and the adaptability of the item to the property.

A built-in bookshelf is attached to the structure of the home and is designed to be part of the overall property, making it a fixture. Similarly, a hanging light fixture is permanently installed and serves a function that is integral to the property's design, thereby also qualifying as a fixture. An air conditioning unit installed in a window, while possibly removable, is generally intended to serve the property and meets the criteria for a fixture.

In contrast, a free-standing refrigerator is not permanently attached to the property; it can be easily moved without causing damage. It remains personal property since it does not become a part of the real estate in the same way that the other items do. Therefore, among the choices provided, the free-standing refrigerator is the item that is not considered a fixture.