Final answer:
For negative-pressure ventilation to work effectively, the opening around the fan must allow air to be drawn in. Additionally, the warming and humidifying of air in the nasal passages serve multiple functions, including preventing lung damage, fighting infection, and reducing breathing sensitivity.
Step-by-step explanation:
Negative-pressure ventilation is a type of mechanical ventilation that involves the creation of a vacuum to draw air into the lungs. For negative-pressure ventilation to be effective, the opening around the fan needs to allow air to be drawn in, which means that the correct answer is (b) Allows air to be drawn in. This ensures that there is a sufficient flow of air that can replace the indoor air to maintain a healthy respirable environment.
Addressing another aspect of indoor air quality and respiration, when air is warmed and humidified in the nasal passages, this process helps to prevent damage to the lungs, ward off infection, and decrease sensitivity during breathing, indicating that the correct response is (d) all of the above.