What type of hair exhibits a strong response to humidity, making it less manageable?

The type of hair that exhibits a strong response to humidity and becomes less manageable is human hair. Human hair is made up of a structure that can absorb moisture from the air, which causes it to swell and change its texture. This absorption leads to frizz and curl, making styling particularly challenging in humid conditions.

In contrast, synthetic hair is typically made from plastic fibers that do not absorb moisture in the same way, making it more stable in varying humidity levels. While curly hair can also be challenging in humid environments, the question specifically seeks a type that reacts strongly to humidity, which is a characteristic most commonly associated with human hair due to its natural properties. Processed hair can refer to various treatments but does not inherently define the response to humidity.