In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.

Ex Input:
Question: How many people did Arnstadt command as a company commander of the 6th border company in Dermbach? Passage:In June 1949, Arnstadt registered for service with the Volkspolizei, the police force of the Soviet Occupation Zone, becoming an Anwärter der VP (police cadet) with the Kasernierte Volkspolizei in Gotha. In March 1950, Arnstadt was appointed to the German Border Police (Deutsche Grenzpolizei) in Dermbach, patrolling the Inner German border with West Germany. In 1952, Arnstadt failed his first attempt to become an officer at the police school in Sondershausen. In 1953, his marriage ended in divorce, with his two children Veronika and Uwe staying with the mother, and remarried shortly after. In 1954, Arnstadt passed his officer training at Sondershausen and was appointed the rank of Unterleutnant, and the following year was promoted to lieutenant. Arnstadt functioned as a recruiter for the German Border Police until 1957 when he was appointed as a company commander of the 6th border company in Dermbach. Arnstadt was responsible for a section of the border at Wiesenfeld, a region of Bezirk Suhl in the Rhön Mountains at the westernmost point of the Warsaw Pact. Arnstadt's section contained the highly-strategic Fulda Gap, which aroused the special interest of NATO, and a short distance from the US Army's Observation Post Alpha. Arnstadt moved with his wife to Wiesenfeld and in April 1957 became an unofficial collaborator (Geheimer Informator) of the Ministry for State Security (Stasi) until this relationship was ended fourteen months later. 
 Links: a. Company commander b. Inner German border c. Dermbach d. Kasernierte Volkspolizei

Ex Output:
a


Ex Input:
Question: Who was older when Heitler obtained his doctorate, Arnold Sommerfeld or Karl Herzfeld? Passage:In 1922, Heitler began his study of physics at the Karlsruhe Technische Hochschule, in 1923 at the Humboldt University of Berlin, and in 1924 at the Ludwig Maximilian University of Munich (LMU), where he studied under both Arnold Sommerfeld and Karl Herzfeld. The latter was his thesis advisor when he obtained his doctorate in 1926; Herzfeld taught courses in theoretical physics and one in physical chemistry, and in Sommerfeld's absence often took over his classes. From 1926 to 1927, he was a Rockefeller Foundation Fellow for postgraduate research with Niels Bohr at the Institute for Theoretical Physics at the University of Copenhagen and with Erwin Schrödinger at the University of Zurich. He then became an assistant to Max Born at the Institute for Theoretical Physics at the University of Göttingen. Heitler completed his Habilitation, under Born, in 1929, and then remained as a Privatdozent until 1933. In that year, he was let go by the university because he was Jewish.
 Links: a. University of Göttingen b. Ludwig Maximilian University of Munich c. Arnold Sommerfeld d. Arnold Sommerfeld

Ex Output:
c


Ex Input:
Question: How old was Ranald's father when he died? Passage:The Norse-Gaelic Clan Donald traces its descent from Dòmhnall Mac Raghnuill (d. circa 1250), whose father Reginald or Ranald was styled "King of the Isles" and "Lord of Argyll and Kintyre". Ranald's father, Somerled was styled "King of the Hebrides", and was killed campaigning against Malcolm IV of Scotland at the Battle of Renfrew in 1164. Clan Donald shares a descent from Somerled with Clan MacDougall, who traces their lineage from his elder son, Dugall mac Somhairle. Their dynasties are together commonly referred to as the Clann Somhairle. Furthermore, they are descended maternally from both the House of Godred Crovan and the Earls of Orkney, through Somerled's wife Ragnhildis Ólafsdóttir, daughter of Olaf I Godredsson, King of Mann and the Isles and Ingeborg Haakonsdottir daughter of Haakon Paulsson, Earl of Orkney. It remains uncertain if the Clann Somhairle are also descendants in some manner, through one or another of the above dynasts, of the House of Ivar, but this is commonly argued.
 Links: a. Somerled b. Uí Ímair c. Haakon Paulsson d. Kingdom of the Isles

Ex Output:

a