All three vehicles want to turn left. Which is in the correct lane?

Your answer is correct because, according to German traffic rules, when turning left, you must be in the leftmost lane designated for left turns. In this situation, the yellow car (vehicle 1) is correctly positioned in the left lane meant for left turns.

The truck and the green car are in lanes not designated for left turns. The truck is in the right lane, which is typically meant for going straight or right, and the green car is on tram tracks, which are generally not supposed to be used by cars for turning left unless specific signs allow it.

So, the rule to remember is: for a left turn, always choose the leftmost lane that is marked or designated for that purpose. This ensures safe and orderly traffic flow and prevents conflicts with vehicles going straight or turning right.