What feature distinguishes ridge lines from other hair design elements?

Ridge lines are a key element in hairstyling that serve a distinct purpose. They are characterized by their ability to connect alternating structured shapes, which allows hairstylists to create dimension and flow within a hairstyle. This connection enhances the visual appeal and helps to maintain a cohesive design throughout the hair.

The other options do not accurately capture the defining feature of ridge lines. For example, ridge lines are not exclusive to formal hairstyles; they can be used in various styles, including casual ones. Additionally, while many ridge lines may be curved, they can also include straight elements depending on the overall design concept. Describing ridge lines as unpredictable in styling does not accurately reflect their systematic role in establishing shapes and patterns in hair design.

Thus, the essence of ridge lines lies in their function to create connections between structured shapes, enabling stylists to achieve desired looks effectively.