Which of the following substances helps another substance retain moisture?

The correct choice is humectant because humectants are substances that attract and retain moisture in food products. They serve an essential role in preventing dryness and maintaining the texture and palatability of various foods. By drawing water vapor from the environment or keeping moisture within the food itself, humectants enhance shelf life and improve the overall eating experience.

For instance, humectants are often used in baked goods, candies, and certain dairy products to ensure they remain moist and do not become stale. This property is fundamental in the food industry, especially in products that are susceptible to drying out.

Preservatives focus more on preventing spoilage or extending shelf life by inhibiting microbial growth, while emulsifiers help combine ingredients that normally do not mix, such as oil and water. Stabilizers serve to maintain the desired consistency or texture in food products but do not inherently retain moisture. Thus, humectants are specifically designed for moisture retention, making them the most appropriate choice in this context.