Parking is prohibited closer than 50 meters to railway crossings. At exactly 50 meters it is allowed, so of the distances given, it is prohibited only at 25 meters.
The law prohibits parking at railway crossings and closer than 50 meters to them (clause 86). At 25 meters the vehicle is in the prohibited zone, so parking there is not allowed. Parking is allowed at exactly 50 meters and farther. Keeping the area next to the crossing clear makes sure other drivers can clearly see approaching trains and the traffic light signals.
Option 1. 300 meters is beyond the 50-meter limit, so parking is allowed here.
Option 2. 150 meters is beyond the 50-meter limit, so parking is allowed here.
Option 3. 100 meters is beyond the 50-meter limit, so parking is allowed here.
Option 4. The prohibition applies only to distances strictly less than 50 meters, so parking at exactly 50 meters is allowed by law.