Which art style is characterized by flowing lines, flat shapes, and depictions of nature?

The art style characterized by flowing lines, flat shapes, and depictions of nature is indeed Art Nouveau. This movement, which flourished from the late 19th century to the early 20th century, is known for its organic forms and intricate designs that are often inspired by natural elements such as flowers, plants, and the human figure. The flowing lines typical of Art Nouveau create a sense of movement and rhythm, which is a significant aspect of the style.

Artists and designers in this movement sought to create harmony between the decorative arts and nature, emphasizing elegant curvilinear forms and intricate details. The emphasis on aesthetics and the integration of art into everyday life were distinctive features of Art Nouveau, making it a unique moment in art history.

In contrast, other styles such as Art Deco focus more on geometric shapes and luxury, while Modernism tends toward abstraction and the rejection of past styles. Impressionism, while advancing new ways of seeing light and color, does not fit the specific characteristics of flowing lines and flat shapes emphasized in Art Nouveau.