What is included under the definition of a natural barrier?

The definition of a natural barrier encompasses physical features that occur in nature and hinder movement or create obstacles in the environment. Cliffs, lakes, and mountains serve as significant examples of natural barriers because they are formed through geological processes and are not created by human intervention. These features can restrict access, direct water flow, affect wildlife movement, or influence weather patterns, making them important elements in the study of geography and environmental science.

In contrast, roads and pathways are human-made structures designed for transportation, and buildings and construction sites are also the result of human activity. Temporary structures, by definition, are not permanent fixtures in the landscape and do not qualify as natural barriers since they are often constructed for limited-duration use. Therefore, natural barriers are specifically defined by their existence in the natural landscape, which is why the correct answer focuses on cliffs, lakes, and mountains.