Which of the following sprinkler systems is most likely to be used in a residence?

The choice of NFPA 13D as the appropriate sprinkler system for residential use is based on its specific design criteria tailored to meet the needs of one- and two-family dwellings and certain townhouses. This standard emphasizes life safety and property protection in lower-hazard residential environments.

NFPA 13D systems are typically designed to cover areas with fewer hazards, using a less intense coverage plan compared to more commercial standards like NFPA 13, which is intended for larger buildings with greater fire risks. NFPA 13R offers a compromise between residential and commercial applications but is still more complex than NFPA 13D, focusing on protecting residential occupancies with more occupants or larger areas.

Furthermore, NFPA 20 pertains to the installation of fire pumps in various applications and does not apply directly to the layout of fire sprinkler systems in residential buildings. Thus, the selection of NFPA 13D is justified as it aligns perfectly with the requirements for safety and effectiveness in residential settings.