Exam CFPS topic 1 question 94 discussion

The nature of the mechanical systems is to use networks of pipes and ducts to connect various parts of the building. Even when the systems are off, these networks can provide routes through the building that allow the spread of fire, smoke, and biological or chemical compounds, causing the danger to spread beyond the hazard's origin. Which of the following is considered to be a building design element that can limit the likelihood of such a system from spreading fire, smoke or chemicals through a building?