Final answer:
None of the given options precisely match the standard maximum length of a semi-trailer, which is usually 53 feet. However, the closest from the options is 55 feet, which exceeds the standard length, and therefore, it is the best option given the choices.
Step-by-step explanation:
According to regulations, there are limits to how long different types of vehicles can be when operating on public roads. For semi-trailers operating in a truck tractor-semitrailer combination, and for trailers drawn by a motor vehicle, the legal length is often prescribed by state and federal laws. Although different states may have different regulations, the typical maximum length allowed for a semi-trailer in commercial transportation on interstate highways without a special permit is often 53 feet. This length regulation is put in place to ensure safety and maneuverability on the road.
In the context of your multiple-choice question, none of the options provided, such as 45 feet, 50 feet, 40 feet, or 55 feet, match the standard 53-foot measurement, which is generally accepted for semi-trailers. It is important to check the specific laws in your jurisdiction, as they may vary. Despite this, for educational purposes, if forced to choose from the options provided, option d. 55 feet is the closest to the typical length of a modern long-haul truck trailer, though it may not be entirely accurate for every situation or location.