When are you obliged to change to the right lane after an overtaking monoeuvre?

In the photo, you are driving in the left lane on a snow-covered road through a forest and overtaking a passenger car, and further ahead there is a white van. After you finish overtaking, you are obliged to return to the right lane when you are sure that there is no risk of cutting in on the overtaken vehicle - answer C. Seeing the rear of the car in the right-hand mirror (A) is only a practical tip, and the distance of 100 m (B) is made up.

The Road Traffic Act requires you to exercise particular caution when overtaking, and when changing lanes - to give way to a vehicle travelling in the lane you intend to move into; it also requires you to drive as close as possible to the right edge of the roadway, so after overtaking you return to the right lane, but not earlier than safety allows. Cutting in means moving in front of the overtaken vehicle so close that its driver has to brake or swerve - on snow this would end in a skid. Drivers use a rule: you return to the right lane when you can see the whole front of the overtaken car in the interior mirror, and not only in the side mirror. Before you move over, you switch on the right indicator and check the mirror, and you carry out the manoeuvre smoothly, without jerking the steering wheel.

Legal basis: Art. 24 para. 2, Art. 22 para. 1 and 4 and Art. 16 para. 4 of the Road Traffic Act (Prawo o ruchu drogowym)