Why are you not permitted to overtake in this situation?

You answered correctly because in this situation overtaking is not allowed for two main reasons according to German traffic rules. First, there is a motorbike approaching from the opposite direction, which means oncoming traffic is present. German traffic law (StVO §5) forbids overtaking when oncoming vehicles might cause a dangerous situation. Second, you do not have enough speed to safely complete an overtaking maneuver before encountering the oncoming vehicles. Both conditions make overtaking unsafe and prohibited here. The third option, overtaking being prohibited by a specific road sign or marking, does not apply in this case, so it is not part of the correct answer. Understanding these principles helps you recognize when overtaking is not allowed: always ensure the opposite lane is clear and you can safely complete the maneuver without danger.