Fire doors may close by which of the following methods?

Fire doors are critical components of fire protection within buildings, designed to prevent the spread of fire and smoke and to establish safe evacuation routes. The correct answer indicates that fire doors may close by swinging, sliding, and rolling methods, which reflects the versatility needed in various architectural designs and applications.

Swinging doors are the most common type and are often used in interior spaces; they can be equipped with self-closing mechanisms to ensure they remain closed when not in use. Sliding doors, frequently employed in areas where space is limited, can effectively close off areas without requiring the space needed for a swinging door arc. Rolling doors, which are often used in commercial settings, provide a robust barrier against fire and can be quickly deployed.

This variety of closing methods allows fire doors to be utilized effectively in numerous settings, catering to different building layouts and fire protection requirements. Thus, the correct choice encompasses the full range of mechanisms by which fire doors can function, ensuring compliance with safety regulations and enhancing overall fire safety in structures.