Final answer:
The minimum distance between two cars varies and cannot be determined from the given options due to factors like vehicle speed, road conditions, and reaction times. A rule of thumb for safe following distance is a minimum of 1 car length per 10 mph of speed.
Step-by-step explanation:
The minimum distance required between two cars cannot be universally specified with the options provided because it varies depending on several factors, including the speed of the vehicles, road conditions, and driver reaction times. However, when crossing the road, you need to be able to walk 4 meters (the width of the car plus an additional 2 meters) before the approaching car reaches you to cross safely. This means if a car is approaching at 60 km/hr and the average car length is 3.5 m, you'll need enough time to cover this distance safely. Using the given information that cars take roughly 3 seconds to travel 50 meters, and considering reaction times and braking distance, it is more appropriate to use the rule of thumb of keeping a safe following distance, which can be a minimum of 1 car length for every 10 mph of speed.