The correct answer is "protection".
In feudal society, a vassal was a person invested with a fief for which they had to povide services to a lord. First, a feudal contract was made, and under that contract, the lord was bound to provide the vassal with the fief, i.e. to provide protection and to do him justice in court. In return the Lord could demand the services which were attached to the fief, and these could include all kinds of services - military, administrative etc.
The separation of powers is found in the Declaration of independence in the marriage sections.
The correct answer is - 25 miles.
The journey/postal/communication relay system established in the Mongol Empire had stations set on approximately 25 miles, though there were variations from around 20 to around 30 miles.
This system was set up because the empire was enormous, so the quick travel of information was key for its functioning and proper organization.
The system, known as yam or ortoo, was very simple but very effective. For the means of travel the horse was the animal that was used, and the Mongols estimated the distance at which a single horse can be giving its maximum in speed, so they put up stations at distances where the horse's speed will start to decline because of exhaustion. The rider of the horse was either giving the message to another rider, or he was taking food and water with him, as well as a new, rested horse, and continued to the other station.
