In this situation, why do you have to wait before turning left?

In this situation, you must wait before turning left because of the motorbike. In German traffic law, when you want to turn left at an intersection, you have to yield to oncoming traffic—this includes cars, motorbikes, and other vehicles coming towards you from the opposite direction. Oncoming vehicles going straight or turning right always have priority over left-turners unless there is specific signage or signals indicating otherwise. The motorbike is coming from the opposite direction and thus has the right of way, so you must wait for it to pass before making your left turn. The other options—a red car and a cyclist—are not the reason for yielding in this context, so your selection is correct. Always remember to check all oncoming lanes for priority traffic before turning left.