What is true about a "bald" facial marking?

A "bald" facial marking is characterized by a broad area that often covers a significant part of the horse's face, including the forehead, reaching down to the upper lip. This type of marking is distinguished by its extent and the lack of pigmentation in the hair, creating a striking contrast with the surrounding colored areas of the horse's coat.

Understanding this definition places emphasis on the marking's size and coverage, which aligns with the description given in the correct answer. Bald markings are not just small or limited; they significantly alter the horse's appearance. The other options fall short because they either describe narrower markings or imply limitations that do not apply to the broadly defined "bald" marking.