Which of the following is an example of an exclusively climate-adapting structure?

An igloo is an excellent example of an exclusively climate-adapting structure because it is specifically designed to withstand cold temperatures and harsh environments typically found in polar regions. The igloo's unique dome shape and materials—primarily compacted snow—provide effective insulation against the cold, ensuring that the internal temperature remains relatively warm compared to the outside conditions. This structure demonstrates how architecture can directly respond to and adapt to the local climate, utilizing readily available materials to create a comfortable living space in an extreme setting.

In contrast, a treehouse, while adaptable to some extent, does not uniquely address climate issues as its primary design focus is on being elevated among trees rather than specifically designed for climate extremes. A modern skyscraper encompasses various features and design elements, but it generally serves urban needs rather than being solely a product of environmental adaptation. A concrete bunker, although robust and secure, is more focused on protection and strength rather than adapting to and utilizing climate characteristics for comfort.