Impasto is characterized by which of the following?

Impasto is a technique in painting where pigments are applied in thick layers, allowing for pronounced texture and dimensionality on the canvas. This method often results in visible brush strokes, enhancing the visual experience by adding depth and a sense of movement to the work. The thick application of paint allows light to reflect off the surface in varied ways, which can create dynamic effects that enhance the overall composition of the artwork.

In contrast, applying transparent layers represents a glazing technique, where colors are built up in thin, translucent washes to create depth without the thickness characteristic of impasto. The gradual change of colors refers to techniques such as blending or gradation, which create smooth transitions rather than the distinct texture inherent in impasto. A one-session painting without layering typically results in a more immediate or spontaneous style, which may not involve the layered thickness that defines impasto. Therefore, the emphasis on the thickness of application and the visibility of brush marks distinctly characterizes impasto, making it the correct choice.