Final answer:
The one-length hairstyle is an example of using directional lines to create a uniform edge that guides the viewer's gaze around the head.
Step-by-step explanation:
The one-length hairstyle, characterized by hair that is cut to the same length all around the head, exemplifies the use of directional lines. Directional lines guide the viewer's eyes in a certain direction — in this case, the uniform edge of the hair creates a visual line that can be seen as directing the gaze around the head. This is different from other types of lines such as parallel lines, which appear in linear perspective and seem to converge in the distance, or hatching, which are closely spaced lines used to create the effect of shading and three-dimensional form.