What can excessive heat application to hair cause?

Excessive heat application to hair can lead to damage and breakage because high temperatures can weaken the hair structure, compromising its natural protein (keratin) bonds. When hair is exposed to heat beyond recommended levels, it can cause the cuticle layers to lift or become frayed, leading to a loss of moisture and elasticity. As a result, hair may become dry, brittle, and prone to splitting or breaking. This highlights the importance of using appropriate heat settings on styling tools and implementing heat protectant products to safeguard hair integrity during styling processes.

The other choices do not accurately represent the effects of excessive heat. Strengthening hair follicles, improving moisture retention, and enhancing natural shine are typically associated with proper hair care and treatment practices, rather than heat application, which generally has detrimental effects when overused.