Plume discharges must be positioned at least 5 feet above or 20 feet away from any __________ to a building.

The requirement for plume discharges to be positioned at least 5 feet above or 20 feet away from any ventilation inlet is based on safety and code compliance for HVAC systems. Ventilation inlets are critical components that allow fresh air to enter a building. If exhaust or plume discharges are located too close to these inlets, there is a risk that the exhaust gases could be drawn back into the building. This can lead to poor indoor air quality, as harmful gases may infiltrate living spaces, potentially posing health risks to occupants.

By ensuring that plume discharges are adequately distanced from ventilation inlets, the design promotes the effective dissipation of exhaust without contaminating the air supply that is intended for ventilation. This measure is an essential part of maintaining a safe and healthy environment within a building.

The other answer choices do not address the same critical safety concerns. For instance, while distance from rooflines and windows might be relevant, it is the proximity to ventilation inlets that poses the most direct risk of contaminating the air that enters the building.