What is the defining characteristic of a blue roan horse?

The defining characteristic of a blue roan horse is indeed a mix of evenly dispersed black and white hairs. This unique color pattern creates a bluish appearance while maintaining the horse's natural coat color tones, which can be quite striking. Unlike horses that are solid in color or exhibit different combinations of brown and white hairs, a blue roan will have that specific blend that gives it a distinctive look. This color is the result of a combination of the black coat gene with white hairs interspersed throughout, differentiating it from other color patterns in horses.

The other options represent different colors or patterns entirely, illustrating the diverse range of horse coat colors but not describing the specific characteristics of a blue roan.