Which type of house is often associated with the architectural movement around the 20th century, featuring open floor plans?

The Prairie house is closely associated with the architectural movement that emerged in the early 20th century, particularly with the work of Frank Lloyd Wright. This style is characterized by its emphasis on horizontal lines, integration with the landscape, and the use of open floor plans. The open layouts were designed to create fluidity between spaces, enhancing the sense of connectedness both within the home and with the surrounding environment. This architectural approach was a reaction against the more formal, compartmentalized layouts of previous styles, promoting a more casual and natural living experience.

In contrast, while the Craftsman house also features some elements of open design, its focus is more on handcrafted details and natural materials rather than the expansive openness typical of Prairie houses. The Farmhouse style tends to have more traditional configurations with separate rooms, reflecting agrarian lifestyles rather than the innovative spatial concepts of the Prairie movement. Likewise, the Bi-level house is more functional and practical in design rather than focusing on the artistic and spatial philosophies emphasized in Prairie architecture. Thus, the Prairie house is the correct answer as it embodies these key characteristics and historical context.