Final answer:
For a client with oily skin like Laura's, a gel-based medium is recommended as it is water-based and will not add extra oil to the skin.
Step-by-step explanation:
Laura has a client with oily skin. The type of massage medium that should be used for a client with oily skin is d) Gel-based. Unlike oil or cream-based products, gel-based massage mediums are lighter and often water-based, which means they are less likely to further clog the pores or add extra oil to the skin which can exacerbate oily skin issues.
Considering the different types of emulsions, oil-in-water and water-in-oil creams have different properties. Oil-in-water creams contain small droplets of oil dispersed in a water phase and are easier to wash off, making them less suitable for oily skin. On the other hand, water-in-oil creams have droplets of water dispersed in oil, providing a more moisturizing effect but can be too greasy for those with oily skin. Gel-based mediums are less likely to leave a greasy residue and provide a comfortable feel while still allowing the skin to breathe, making them the preferred choice for oily skin types.