A sign has been placed at a distance of about 100 metres before a railway crossing, and a slow vehicle is travelling ahead of you:

1. AYou may overtake the vehicle only when the speed does not exceed 35 km/h.
2. BYou may not overtake the vehicle until you have crossed the crossing.
3. CYou may overtake the vehicle even before the crossing.
4. DYou may overtake the vehicle only when the road ahead is clear.

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