The type of hair that is most susceptible to damage from chemical treatments is:

Fine hair is most susceptible to damage from chemical treatments due to its delicate structure. Fine hair generally has a smaller diameter, which can make it more fragile and less able to withstand harsh chemical processes such as coloring, perming, or relaxing. The cuticle layer, which protects the hair shaft, is often thinner in fine hair, making it more vulnerable to breakage and overall damage when exposed to chemicals.

Additionally, fine hair is more easily saturated with chemical solutions, leading to potential over-processing. This can result in increased porosity and further weaken the hair structure. Therefore, when considering hair types and their resilience, fine hair stands out as particularly sensitive to the effects of various chemical treatments, necessitating careful handling and specialized products to minimize potential damage during these processes.