Final answer:
The type of massage medium that is not listed is 'scrub'. Massage mediums include gels, oils, and creams, while a scrub is more of a skin exfoliant.
Step-by-step explanation:
The item in the list that is not a type of massage medium is c. scrub. A massage medium is a substance used to reduce friction between the skin and the hands of the massage therapist. Common mediums include gels, oils, and creams. Unlike these mediums, a scrub is a form of skin treatment that includes granular substances to exfoliate and remove dead skin cells, rather than to lubricate the skin for massage.
Conditions like dry skin can be treated with topical moisturizers such as lotions, creams, or oils. While lotions have a lower viscosity and higher water content, creams and gels are thicker due to their lower water content. It's important to note that some skin issues are preventable by eliminating pressure points and can result from deep massages if not performed correctly or with adequate medium.