What is the primary function of the MAN V/S CTL Switch?

The primary function of the MAN V/S CTL switch is indeed to control cabin altitude. This switch allows the flight crew to manage the rate of climb or descent of the cabin pressure manually. When the switch is set to the MAN (manual) position, it enables the crew to directly control the pressurization system, which is particularly important during abnormal conditions or when there is a need for specific pressurization management. By allowing manual control over the pressurization system, the crew ensures that the cabin altitude remains within a safe range for passenger comfort and safety.

The other choices, while related to cabin pressurization, do not accurately describe the primary function of the MAN V/S CTL switch. Monitoring the pressurization systems is a necessary operational task but does not involve direct control, and the switch does not adjust landing elevation or switch to automatic pressurization, which is managed differently in the aircraft systems.