Final answer:
The phrase 'thick and shiny' is descriptive of the oily skin type due to the overproduction of sebum, giving the skin a glossy appearance.
Step-by-step explanation:
The descriptive phrase "thick and shiny" typically identifies an oily skin type. Oily skin types tend to have a shinier appearance due to the excess sebum produced by the skin's sebaceous glands. This can often lead to the skin appearing thicker and more glossy in comparison to other skin types. The thickness mentioned in Figure 5.3, however, refers to the thickness of the epidermal layer rather than being a characteristic of oily skin specifically. This is more related to skin anatomy than to the skin types typically discussed in skincare, which are generally characterized by the amount of oil production.