What is the dorsal stripe typically associated with?

The dorsal stripe is a prominent feature in the coloration patterns of grullo horses, which are a type of dilution color resulting from the presence of a specific genetic factor in their coat. This stripe runs along the spine from the mane to the tail and is often darker than the rest of the body, which can be a grayish-blue color. The presence of this stripe is a defining characteristic of grullo horses because it helps distinguish them from other equine colors and patterns, making the dorsal stripe a strong indicator of this specific coat color.

The other options refer to different patterns and colors in horses. Pinto patterns describe a horse with large patches of white and another color, while red roan horses feature a mix of red and white hair, but neither typically includes a dorsal stripe as a defining characteristic. Tabiano horses, or the "Tobiano" pattern, is similar to pinto but has its own distinctive markings that do not include a dorsal stripe. Thus, the association of the dorsal stripe with grullo horses is what makes this choice the most accurate in the context of horse coloration traits.