Which ingredient type acts primarily as a cleaner in formulations?

Surfactants serve as cleansing agents in formulations due to their unique molecular structure, which allows them to reduce surface tension between substances. This characteristic enables them to emulsify oils and trap dirt and impurities, allowing for effective cleansing. In skincare and cosmetic products, surfactants help to lift away debris from the skin's surface and facilitate the removal of excess oils, making them essential in formulations such as facial cleansers and body washes.

Humectants, while important in maintaining skin moisture by attracting water, do not primarily function as cleaners. Instead, they help to hydrate the skin. Emollients are ingredients that soothe and soften the skin, providing a smooth texture but again do not contribute to cleansing. Occlusives are substances that create a barrier on the skin to prevent moisture loss, but they don't clean the skin. Therefore, the primary role of surfactants as cleaners makes them the correct choice for this question.