When a heavy rigid truck or articulated combination vehicle makes a right turn at an urban intersection, what primary factor creates the hazardous right-side blind spot often referred to as the 'Death Zone' (死亡盲区)?

1. The inner wheel difference (内轮差), where the rear wheels follow a significantly tighter turning arc than the front steering wheels
2. The aerodynamic downforce created by the front bumper deflecting side airflow
3. The pneumatic brake lag between the foot valve and the trailer relay valve
4. The reflection of the curb mirror distorting distance perception in direct sunlight