Final answer:
The percentage of outside air used for positive pressurization in smoke removal systems varies depending on the system, as it is dependent on the building design, local codes, HVAC specifics, and the intended smoke control strategy.
Step-by-step explanation:
The percentage of outside air used for positive pressurization in smoke removal systems is not a fixed value and can vary based on multiple factors. These factors include the design of the building, the local building code requirements, the specifics of the HVAC system, and the smoke control strategy being implemented. There are engineering guidelines and building regulations that recommend the appropriate rates of outdoor air for pressurization, but because each building and smoke control system can have unique characteristics, it is important for the system to be designed to meet the specific needs of the building.
Therefore, the correct answer to the question is: d) It varies depending on the system.