Which of the following contributes to the barrier function of moisturizing creams?

Moisturizing creams are designed to improve the skin's hydration and protect its barrier function. Emollients play a crucial role in this process because they are ingredients that help soften and soothe the skin. They work by filling in the gaps between skin cells, which helps to create a smoother surface and improve the skin's ability to retain moisture. This action is essential for maintaining the skin's barrier function, which prevents water loss and protects against environmental irritants.

While other components like colorants and fragrances might enhance the sensory experience of a product, they do not contribute directly to moisturizing or barrier protection. Preservatives are important for ensuring the product's safety and longevity by preventing microbial contamination but also do not play a role in the moisturizing aspects of the cream. Thus, emollients are the key ingredients that directly support and enhance the barrier function in moisturizing creams.