Which of these is an intrinsic effect on the skin?

The correct answer is the option that describes an intrinsic effect on the skin, which is related to internal factors affecting skin health. Vitamin deficiency represents an intrinsic factor because it originates from within the body, reflecting dietary habits and nutrition. Insufficient vitamins can lead to various skin issues such as dryness, irritation, or delayed healing. This impact is more directly tied to the body's internal environment rather than external influences.

In contrast, the other options highlight external factors. Exposure to UV light is an environmental factor that can lead to skin damage from the sun, including photoaging and skin cancer. Misuse of products typically involves external applications that may irritate or damage the skin barrier. Similarly, pollution refers to environmental contaminants that can affect skin health through their interaction with the skin's surface. These external factors can indeed impact the skin but are not classified as intrinsic. Understanding the distinction between intrinsic and extrinsic factors is essential in skin analysis and developing effective skincare regimens.