Which two switches must be OFF to prevent right side P3 bleed air from entering the cockpit?

To prevent right side P3 bleed air from entering the cockpit, the correct switches to have OFF are the BLEED AIR INFLOW and DEFOG. The BLEED AIR INFLOW switch is specifically responsible for controlling the amount of bleed air that can enter the cabin from the engines; having this switch OFF will ensure that no bleed air can enter the cockpit area.

The DEFOG switch, on the other hand, is designed to direct airflow to the windshield to manage fogging conditions. When the DEFOG switch is ON, it can potentially allow bleed air into the cockpit to provide the necessary airflow for defogging purposes. Therefore, by having both the BLEED AIR INFLOW and the DEFOG switch OFF, you are effectively preventing any P3 bleed air from entering the cockpit, ensuring a safe and controlled environment within the aircraft.

The other choices involve switches that either do not control the flow of bleed air directly or do not work in conjunction to maintain the cockpit environment effectively in relation to bleed air concerns. Understanding the function of these switches is crucial for pilots and crew when managing cabin pressure and air quality.