Which of the following is considered an out-of-the-ordinary opening?

A fireplace or mantle is regarded as an out-of-the-ordinary opening due to its unique characteristics and function compared to typical doorways and windows. While standard openings, such as window frames and doorframes, serve conventional purposes and adhere to standard construction practices, a fireplace represents a specialized architectural feature that is not only functional but also serves as a focal point in a room. The installation and design of a fireplace and mantle usually involve considerations for aesthetics, heat distribution, and safety, which differ significantly from standard openings. This complexity in design and function clearly categorizes it as out of the ordinary in the scope of architectural features.