Which of the following is a characteristic of surfactants?

Surfactants are unique compounds that possess distinct properties enabling them to lower surface tension between liquids or between a liquid and a solid. One of their primary functions is to promote lathering and foam. By allowing water and air to mix more easily, surfactants help create bubbles and lather, which is particularly valuable in many cleansing and cosmetic formulations. This foaming action is essential in products such as shampoos, facial cleansers, and body washes, contributing to the consumer's experience and effectiveness of the product.

The other characteristics mentioned in the choices do not encompass the primary functions of surfactants. While some surfactants may slightly influence product viscosity, their main purpose is not to thicken products. Enhancing product scent and acting as skin protectants are roles typically associated with fragrance ingredients and emollients or moisturizers, respectively, rather than surfactants themselves. Thus, the key characteristic of surfactants is their ability to generate lather and foam, making option B the most accurate description.