Final answer:
The correct answer is 50 ft (option a). Passing at a distance closer than 50 ft to an intersection or railroad crossing is considered illegal as it compromises safety and can lead to accidents.
Step-by-step explanation:
In the given question, the student is asking about the distance at which it is illegal to pass if they are closer to an intersection or railroad crossing. The correct answer is 50 ft (option a). Passing at a distance closer than 50 ft to an intersection or railroad crossing is considered illegal as it compromises safety and can lead to accidents. It is important to obey traffic laws and maintain a safe distance from intersections and railroad crossings.