Indiana State Beauty Practice Exam

Zinc oxide is a widely used ingredient in sunscreen due to its effective protective properties against ultraviolet (UV) rays. It acts as a physical blocker, meaning that it sits on the surface of the skin and reflects and scatters UV radiation, protecting the skin from damage that can lead to sunburn, premature aging, and even skin cancer.

In contrast, glycerin is a humectant that is primarily used for hydration and does not offer UV protection. Alcohol, while used in some formulations, may have drying effects on the skin and doesn't provide sun protection. Mineral oil is primarily used as a moisturizer and does not have the photoprotective benefits that zinc oxide offers. Therefore, zinc oxide is the ingredient recognized for its dual role as a protective agent against harmful UV radiation in sunscreens.