According to the NFPA guidelines, how should horizontal termination of a mechanical draft venting system be arranged?

The correct choice emphasizes the importance of safety in the installation and maintenance of mechanical draft venting systems. According to NFPA guidelines, the horizontal termination of such systems must be designed to prevent harmful effects on people and structures. This involves ensuring that exhaust gases are expelled away from areas where people congregate and are directed away from windows, doors, and other openings that could lead gases back into living spaces.

By prioritizing the prevention of harm, adherence to NFPA guidelines helps reduce the risk of carbon monoxide poisoning, fire hazards, and other safety issues that can arise from improper venting. This aspect of safety is fundamental in residential and commercial applications, making it essential for installers and builders to follow these guidelines closely.

While other considerations like airflow efficiency, fuel consumption, and maintenance access are important in creating a functional and efficient system, safety is always a top priority as per the NFPA's directives. These guidelines ensure not only the efficient operation of the venting system but also the protection of occupants and property.