What is commonly known as a "liver spot"?

A "liver spot" is commonly referred to as solar lentigo. These are flat, brown spots that typically appear on areas of the skin that have been frequently exposed to the sun, particularly on the face, hands, shoulders, and arms. They are a result of increased melanin production due to sun exposure and are often harmless, serving as a sign of sun damage.

Understanding the nature of solar lentigo is important, as these spots tend to develop with age, particularly in individuals with fair skin. While other terms in the options refer to different skin conditions or pigmentation, solar lentigo specifically addresses the brown spots seen in sun-exposed areas, making it the correct answer in this context.