Information:  - Russia (from the  Rus'), also officially known as the Russian Federation, is a country in Eurasia. At , Russia is the largest country in the world by surface area, covering more than one-eighth of the Earth's inhabited land area, and the ninth most populous, with over 140 million people at the end of March 2016. The European western part of the country is much more populated and urbanised than the eastern, about 77% of the population live in European Russia. Russia's capital Moscow is one of the largest cities in the world, other major urban centers include Saint Petersburg, Novosibirsk, Yekaterinburg, Nizhny Novgorod and Samara.  - A diploma (from Greek µ "díplma", meaning "folded paper") is a certificate or deed issued by an educational institution, such as a college or university, that testifies that the recipient has successfully completed a particular course of study, or (US) recording that an academic degree has been awarded. In some countries, e.g. the United Kingdom and Australia, the word diploma also refers to an academic award (e.g. diploma of higher education, graduate diploma, postgraduate diploma). Historically, it can also refer to a charter or official document, thus diplomatic, diplomat and diplomacy via the "Codex Juris Gentium Diplomaticus".  - A diplomat is a person appointed by a state to conduct diplomacy with one or more other states or international organisations. The main functions of diplomats are: representation and protection of the interests and nationals of the sending state; initiation and facilitation of strategic agreements; treaties and conventions; promotion of information; trade and commerce; technology; and friendly relations. Seasoned diplomats of international repute are used in international organisations (e.g. United Nations) as well as multinational companies for their experience in management and negotiating skills. Diplomats are members of foreign services and diplomatic corps of various nations of the world.  - Saint Petersburg is Russia's second-largest city after Moscow, with five million inhabitants in 2012, and an important Russian port on the Baltic Sea. It is politically incorporated as a federal subject (a federal city). Situated on the Neva River, at the head of the Gulf of Finland on the Baltic Sea, it was founded by Tsar Peter the Great on May . In 1914, the name was changed from Saint Petersburg to Petrograd, in 1924 to Leningrad, and in 1991 back to Saint Petersburg. Between 17131728 and 17321918, Saint Petersburg was the imperial capital of Russia. In 1918, the central government bodies moved to Moscow.  - Pyotr Petrovich Troubetzkoy , ( 1822 -- 1892 ) was a Russian diplomat , administrator and general . Troubetzkoy was born in Tulcin in 1822 . His first wife was Varvara Yourievna Troubetzkoy . In 1844 he was appointed governor of Smolensk , and Orel . In 1865 he went to Florence ( Italy ) on a diplomatic mission which included the supervision of the Russian church there . In Florence he met Ada Winans , an American lyric singer , and with her moved to Ghiffa on Lake Maggiore . Troubetzkoy divorced Varvara in 1870 and married Ada . He could then recognize his three sons born from Ada : Pierre ( husband of American novelist Amélie Louise Rives ) , Paul and Luigi . Keen on botany , Piotr found in Ghiffa the best place to develop an important botanic garden and build his residential Villa . In 1884 , owing to the financial disaster of the Panama canal construction he was forced to sell the villa in Ghiffa and , separated from Ada , he retired with Marianna Hahn first in Milano where was born their natural son Pietro Troubetzkoy Hahn 1886 , and finally to Menton ( France ) where he died in 1892 .    After reading the paragraphs above, we are interested in knowing the entity with which 'peter troubetzkoy' exhibits the relationship of 'given name'. Find the answer from the choices below.  Choices: - an  - are  - e .  - juris  - peter
A:
peter