Which of the following best describes a sewage stack?

A sewage stack is best described as a vertical pipe that transports sewage from various plumbing fixtures down to the building's drainage system. This function is crucial in removing waste effectively from bathrooms, kitchens, and other areas equipped with plumbing systems. The vertical orientation of the sewage stack allows for efficient gravity flow of waste, ensuring that sewage can move downward without obstruction.

The correct characterization emphasizes its primary role in the plumbing system. While other options mention aspects such as ventilation or connections between drains, they do not accurately define the primary function of a sewage stack, which is to carry sewage vertically from fixtures to the drain system of the building. This distinction is essential for understanding how plumbing systems are designed to manage waste efficiently and effectively.