Given the question: Information:  - An "official" is someone who holds an office (function or mandate, regardless whether it carries an actual working space with it) in an organization or government and participates in the exercise of authority (either their own or that of their superior and/or employer, public or legally private).  - Latin (Latin: ) is a classical language belonging to the Italic branch of the Indo-European languages. The Latin alphabet is derived from the Etruscan and Greek alphabets.  - In many countries, a mayor (or , from the Latin "maior" , meaning "bigger") is the highest-ranking official in a municipal government such as that of a city or a town.  - This is a list of mayors of Chur . The mayor of Chur held the title of Bürgermeister until 1875 . Since then , the Stadtpräsident presides the city 's executive , the office of the Bürgermeister is limited to the presidency of the local citizen 's corporation ( Bürgergemeinde ) .  - Chur or Coire (or ; or ; ) is the capital and largest town of the Swiss canton of the Grisons and lies in the Grisonian Rhine Valley, where the Rhine turns towards the north, in the northern part of the canton. The city, which is located on the right bank of the Rhine, is reputedly the oldest town of Switzerland.  - The Rhine (, , ) is a European river that begins in the Swiss canton of Graubünden in the southeastern Swiss Alps, forms part of the  Swiss-Austrian, Swiss-Liechtenstein, Swiss-German and then the Franco-German border, then flows through the Rhineland and eventually empties into the North Sea in the Netherlands.  The largest city on the river Rhine is Cologne, Germany, with a population of more than 1,050,000 people. It is the second-longest river in Central and Western Europe (after the Danube), at about , with an average discharge of about .  - A town is a human settlement larger than a village but smaller than a city. The size definition for what constitutes a "town" varies considerably in different parts of the world.    After reading the paragraphs above, choose the best answer for the entity that related to 'list of mayors of chur' with the relationship of 'located in the administrative territorial entity'.  Choices: - canton  - chur  - cologne  - europe  - germany  - graubünden  - of  - rhine  - switzerland
The answer is:
graubünden