After Darius I restored order to the Persian Empire, he built many roads to connect parts of the empire. Source taken from Herodotus - History of the Persian Wars. Here is one quote: “Nothing mortal travels so fast as these Persian messengers...these men will not be hindered from accomplishing at their best speed the distance which they have to go, either by snow, or rain, or heat, or by the darkness of night.” This is the primary source taken from the writings on Herodotus in "The History of the Persian Wars".
Question: Which of the following is the best way to summarize this passage? Basically, what is the author trying to say?