Where shall vehicles not be parked or left unattended?

The appropriate location for not parking or leaving vehicles unattended is indeed in areas designated by a NO PARKING sign. These signs are specifically placed to ensure safe and efficient operation of airport activities, including the movement of aircraft and other vehicles. By adhering to these regulations, operators help prevent obstructions that could lead to potential hazards and delays.

Positions marked with a NO PARKING sign are often critical for maintaining the flow of traffic and ensuring that emergency access routes remain clear. When vehicles are parked in these areas, it can hinder operations and create unsafe conditions for both personnel and aircraft.

The other options present contexts where parking may typically be regulated but do not universally prohibit unattended vehicles the way a NO PARKING sign does. While vehicles should not be left on a VSR or in areas like taxiing zones, there may be specific circumstances under which vehicles can be present or parked temporarily, provided they do not interfere with operations. However, areas marked by NO PARKING signs are unequivocally prohibited, reinforcing the importance of these regulations in maintaining safety at the airport.