Which of the following is a characteristic of pigmented growth on agar?

Color production is a key characteristic of pigmented growth on agar. When microorganisms grow on agar, they can produce pigments that influence the color of the colony. This production of color is often a result of metabolic processes unique to specific microorganisms and can aid in identification based on the pigment's hue, intensity, and type.

While smooth edges, irregular shapes, and friable textures can describe various colony morphologies or textures, they do not define pigment production. The essence of pigmented growth is indeed tied to the ability of the organism to synthesize colors as part of its biological processes, which can be visualized clearly on the surface of the agar. Color production is thus the definitive aspect when describing pigmented growth characteristics.