Final answer:
Barrel curls have large center openings and are styled in a standing position on a rectangular base, creating a voluminous wave distinct from other curl types.
Step-by-step explanation:
The correct answer to the question is b) Barrel curls. Barrel curls are characterized by their large center openings and are typically fastened to the head in a standing position on a rectangular base. Unlike pin curls, which are small and secured closely to the scalp, or roller curls, which use rollers for setting, barrel curls create a softer and larger wave by being wound around a larger cylinder shape, such as fingers or a curling iron, thus creating a distinctive voluminous look that stands out.