Which substance is known for its sweet, colorless, oily properties?

Glycerin is recognized for its sweet, colorless, and oily properties, making it a versatile compound in various fields. It is a simple polyol compound, which means it contains multiple hydroxyl or alcohol groups that contribute to its hygroscopic nature—allowing it to attract water. This characteristic enables glycerin to function well as a moisturizer in cosmetic products and as a sweetener in food items.

The oily aspect of glycerin comes from its structure as a viscous liquid, which is often used in formulations where a smooth consistency is desired. Additionally, glycerin is generally recognized as safe for consumption and is commonly used in pharmaceuticals, making it an important substance in both medical and culinary applications.

The other options, while they may have various properties, do not fully align with the specific description provided. Aspirin is a medication and does not exhibit the sweet, oily characteristics of glycerin. Glycogen is a storage form of glucose in the body and is not a standalone substance that would fit this description. Glucose, although sweet, is a simple sugar and not oily in nature. Thus, glycerin is the clear answer as it uniquely meets all the specified criteria.