Which of these is a common characteristic of the wind exposure category C?

Wind exposure category C is characterized by more extensive open areas that are generally flat and unobstructed by buildings, trees, or other structures. This category is typically found in areas where the wind can blow freely and is not interrupted by surrounding topography. In this setting, buildings are exposed to higher wind speeds, and it is crucial for building codes and design considerations to account for these conditions to ensure structural integrity and safety.

The other options, while related to wind exposure, do not accurately describe category C. For instance, close proximity to trees and structures suggests an obstruction to wind flow, which is inconsistent with the characteristics of category C. Flat terrain with few obstructions could apply, but in a broader context, extensive open areas are more definitive for this category. Rooftop garden installations do not define wind exposure categories and instead relate more to building design and landscaping, making them irrelevant to the classification of wind exposure. Therefore, option D is the correct answer as it distinctly highlights the nature of wind exposure category C.