Which feature describes the typical structure of a Doric frieze?

The typical structure of a Doric frieze is characterized by the presence of panels and triglyphs, which are distinctive elements of this classical order. In the Doric frieze, the alternating arrangement consists of three vertical grooves (triglyphs) and a panel (metope) that can be plain or decorated. This repetition not only provides a rhythmic pattern but also reflects the simplicity and strength that epitomize Doric architecture.

The use of triglyphs and metopes is integral to the Doric order, as it emphasizes the structural components of the temple, linking back to the traditional wooden structures that preceded stone construction. Additionally, the geometry and proportions involved in their design contribute to the overall aesthetic of balance and harmony, key principles in ancient Greek architecture.

In contrast, the other options do not accurately represent the defining characteristics of a Doric frieze. Regular patterns of architraves, engaged columns, and open pediments may relate to other classical architectural elements or orders, but they do not specifically capture the unique features of the Doric frieze itself. Therefore, choosing the presence of panels and triglyphs is the correct understanding of what defines a Doric frieze.