Which type of door is noted for not having panels?

Flush doors are characterized by their smooth and flat surface without any panels or ornamental designs. They are typically constructed from solid or engineered wood or are made with a core of solid materials, making them strong yet minimalist in appearance. This simplicity allows them to fit seamlessly into a variety of architectural styles, which makes them a popular choice for both residential and commercial applications.

In contrast, panel doors have distinct panels that create a more traditional and decorative look. French doors are known for their multiple glass panels that allow light to pass through, while louver doors feature horizontal slats (or louvers) that provide ventilation and a unique aesthetic. Hence, it is flush doors that stand out due to their absence of panels, affirming their status as the correct answer.