What is a common effect of hydrophobic substances in personal care products?

Hydrophobic substances have a natural tendency to repel water. In the context of personal care products, this characteristic is utilized to create formulations that can effectively keep moisture out, which is beneficial in various applications. For example, hydrophobic ingredients can form a barrier on the skin’s surface, which helps to protect against external elements such as water and sweat. This repellant property is particularly advantageous in products like sunscreens, moisturizers, and makeup, where maintaining a specific skin condition and preventing unwanted moisture absorption is crucial.

The other options, while relevant to skin health and product formulation, do not accurately describe the fundamental role of hydrophobic substances. For instance, they do not enhance skin hydration, provide UV protection, or act as emulsifiers, which relate more to hydrophilic properties or specific functional roles in cosmetic formulations.