Which emulsifying agent is added to an emulsion dressing to help the oil remain suspended?

The correct choice is an emulsifying agent, which plays a pivotal role in stabilizing mixtures of oil and water, such as in an emulsion dressing. An emulsifying agent works by reducing the surface tension between the oil and water, allowing them to mix more thoroughly. In this context, a binder serves as a primary emulsifier that helps keep the oil evenly dispersed throughout the dressing, preventing separation.

While options like clarifiers, gluten, and thickeners have their own roles in food preparation, they do not function as emulsifying agents in the same capacity. A clarifier is used to remove impurities or sediments from liquids. Gluten, a protein found in wheat, affects the texture and elasticity of baked goods rather than acting as an emulsifier. A thickener, on the other hand, can modify the viscosity of a liquid but doesn't stabilize oil-in-water emulsions. The use of a binder as an emulsifying agent is essential for achieving a stable, uniform emulsion in dressings.