Two vehicles approach one another at an intersection. Both vehicles want to turn left. In what exceptional case do they have to turn one after the other?

The combination of answer choices 1 and 2 is correct because both situations involve specific conditions that dictate how vehicles should behave at an intersection.

1. If the road traffic situation demands it: This implies that if there are obstacles, pedestrians, or other vehicles that affect the flow of traffic, then the drivers need to assess those conditions and may need to yield or take turns.

2. If the layout of the intersection demands it: This means that the physical design of the intersection (such as signage, markings, or traffic signals) may require vehicles to take turns even if they are both intending to turn left.

Selecting both options is important because it captures all scenarios where traffic rules require vehicles to avoid simultaneous turns, thereby ensuring safety and order on the roads. This is in line with the principles outlined in the German road traffic regulations, which prioritize safe driving practices and cooperation among road users.