What happens if the cargo door is not closed and locked while the left engine run switch is in the RUN position?

If the cargo door is not closed and locked while the left engine run switch is in the RUN position, it triggers an amber CARGO DOOR caution indication. This caution is a safety mechanism designed to alert the flight crew of a potentially dangerous situation which could compromise the safety of the aircraft.

The logic behind this warning system is that an unsecured cargo door can lead to loss of cargo or cabin pressure, thereby posing risks to the aircraft and its occupants. The amber color signifies caution, indicating that the crew needs to take action to rectify the situation before proceeding with further operations, such as takeoff or climbing to a cruising altitude.

The other options would not be activated in this scenario, as a green indication typically stands for a normal operating condition, while a warning is generally indicated by a different color and condition. Thus, the amber CARGO DOOR caution remains the appropriate response to the scenario described.