Final answer:
It is illegal to stop or park your vehicle on light rail tracks because it poses a danger to public safety and disrupts transportation services.
Step-by-step explanation:
The question pertains to the legality of stopping or parking a vehicle in certain locations. Among the given options, it is illegal to stop or park your vehicle on light rail tracks. This is because it can obstruct the path of the trains, posing a danger to public safety and disrupting public transportation services. On the other hand, stopping or parking on side streets, grass, or country roads may be legal or illegal depending on local traffic laws and whether the vehicle is obstructing traffic or parked on private property without permission.