What material is used to hold moisture in the skin and has sealing properties?

The correct choice is paraffin because it is a popular treatment in the beauty and spa industry known for its ability to retain moisture in the skin due to its occlusive properties. When warmed, paraffin wax adheres to the skin and creates a barrier that traps heat and moisture beneath it. This is particularly beneficial for dry skin, as it helps to hydrate and soften the skin during and after the treatment.

In contrast, disinfecting solutions serve to sanitize surfaces and tools, preventing bacterial growth, and do not have any properties related to moisture retention. Ultraviolet lamps are primarily used for curing nail products such as gel polish, and they do not have sealing properties for skin. Nail polish functions as a protective and decorative coating for nails but does not contribute to moisture retention in the skin. Thus, the unique sealing and moisturizing properties of paraffin make it the appropriate answer.