What is the consequence of having bleed air valves in ENVIR OFF during flight?

The correct choice reflects that setting the bleed air valves to ENVIR OFF during flight results in a loss of pressurization. Bleed air is critical for maintaining cabin pressure by allowing conditioned air from the engines to enter the cabin and ensure a comfortable environment for passengers and crew at high altitudes. When the bleed air valves are turned off, the cabin loses access to this necessary pressurized air supply, which can lead to a rapid descent in cabin pressure. This situation can cause altitude sickness or other physiological issues for those onboard, making it crucial to manage bleed air systems appropriately during flight to ensure safety and comfort.