Which architectural style emphasizes form, simplicity, and proportion, drawing from ancient Greek and Roman principles?

The architectural style that emphasizes form, simplicity, and proportion while drawing from ancient Greek and Roman principles is classical architecture. This style is characterized by its use of columns, symmetry, and harmonious proportions, which were heavily inspired by the architectural achievements of ancient civilizations.

Classical architecture focuses on the ideal of beauty through mathematical ratios and geometric forms, a concept that was central to the designs of ancient Greek temples and Roman structures. Elements such as the Doric, Ionic, and Corinthian orders, which define the styles of columns, highlight this emphasis on proportion and aesthetics.

The other options, while significant in their own right, do not align with the principles of classical architecture. Folk art tends to focus on organic forms and cultural storytelling rather than strict adherence to classical forms and proportions. Art Nouveau emphasizes decorative arts and organic forms, moving away from the rigid structures of classical designs. The Hudson River School represents an art movement focused on landscape painting rather than architecture, drawing inspiration from nature and the American landscape rather than ancient architectural principles. Thus, classical architecture stands as the correct choice due to its foundational basis in the aesthetics of ancient Greek and Roman styles.