What is the defining characteristic of intaglio printing techniques?

The defining characteristic of intaglio printing techniques is that the ink sits below the surface of the plate. In intaglio methods, such as engraving, etching, and drypoint, the image is incised or etched into a plate, leaving the recessed areas to hold the ink. When the plate is pressed onto paper, the paper conforms to the depressions filled with ink, resulting in a print where the image appears in relief against the paper.

The other options describe different printmaking techniques. For example, the first option refers to relief printing, where the image is raised above the non-printing areas, such as in woodcut or linocut methods. The third option is more aligned with monotype or painting techniques, which involve applying paint to a flat surface to create images. Lastly, the fourth option pertains to lithography, a distinct printing process that relies on a flat stone or metal plate and the interplay of oil and water to create images. Each of these methods has unique characteristics that set them apart from intaglio printing.