Which type of hair is most likely to be brittle and dry?

Fine hair is most likely to be brittle and dry because it has a smaller diameter and thinner cuticle layers than other hair types. This makes fine hair more susceptible to damage from environmental factors such as heat styling and chemical treatments, as well as less capable of retaining moisture. Additionally, fine hair often lacks the natural oils that provide hydration and protection, resulting in a dry and brittle texture.

Oily hair typically has a higher concentration of sebum, which can protect against dryness. Coarse hair, while it can be dry, often has more structure and can better withstand wear and tear due to its thicker strands. Curly hair is also at risk of dryness but generally has more volume and structure, which can help hide brittleness better than fine hair. Thus, when considering the susceptibility to brittleness and dryness, fine hair is the most likely candidate.