Which of the following best describes the cause of the Cultural Revolution?

1. knighthood able-bodied men who are hired by the vassal for the protection of the lord 2. standing army a call to appear in court 3. subinfeudation group of soldiers ready to do battle 4. summons a man who would give protection to the lord in exchange for land 5. vassal breaking down an already-smaller portion of land in exchange for services and protection