Which of the following compounds is a type of humectant?

Ethylene glycol is a type of humectant, which means it has the ability to retain moisture. Humectants are substances that can absorb water from the environment or humid air, making them valuable in various applications, such as cosmetics, food products, and pharmaceuticals. Ethylene glycol's chemical structure enables it to form hydrogen bonds with water molecules, allowing it to maintain hydration levels effectively.

This characteristic is particularly important in formulations where moisture retention can improve stability, texture, or flavor. In contrast, the other compounds listed do not have humectant properties. Sodium chloride (table salt) primarily serves a different function, chlorine is commonly associated with disinfection and sanitation, and formaldehyde is primarily used as a preservative and does not retain moisture. Understanding the role of each compound within their contexts helps clarify why ethylene glycol is recognized for its ability to act as a humectant.