Arc pin curls are also known as which of the following?

Arc pin curls, often referred to as C-shape base curls, are characterized by their specific shape that mimics the letter "C." This type of curl is created by wrapping the hair around a pin curl clip in a curved shape, resulting in a natural wave or curl. The curvature allows for greater flexibility and movement in the hairstyle, making them a popular choice for creating soft, flowing curls or waves.

In contrast, other types of curls mentioned have distinct characteristics that do not align with the definition of arc pin curls. For example, no stem base curls lack the ability to create movement at the roots, square base curls have a different angle that can produce more volume and less curl, and S-shape base curls produce a different visual effect and structure than the smoother, more gradual curve of C-shape base curls.