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.

Example Input: Question: Which of the regiments that Ellwood served in was the largest? Passage:Ellwood graduated from Duntroon in 1990 and was commissioned into the Royal Australian Infantry Corps. His early career included postings as a platoon commander in the 2nd/4th Battalion, Royal Australian Regiment and as an instructor in field training and tactics at Duntroon, before he was seconded to the British Army from 1998 for a two-year exchange with the Irish Guards, then stationed in Germany. During the secondment he deployed as part of the NATO intervention in the Kosovo War in 1999, serving as second-in-command of an armoured infantry company in the King's Royal Hussars Battle Group. For his service in Kosovo, Ellwood was awarded a Commander British Forces Commendation. He returned to Australia as a company commander and operations officer in the 5th/7th Battalion, Royal Australian Regiment (5/7RAR). Ellwood commanded B Company on operations in East Timor from October 1999 to April 2000, when 5/7RAR deployed with the International Force East Timor.
 Links: a. 2nd/4th Battalion, Royal Australian Regiment b. Kosovo War c. 2nd/4th Battalion, Royal Australian Regiment d. King's Royal Hussars
Example Output: a

Example Input: Question: What languages did Commandino translate the works fo Aristarchus of Samos and Pappus of Alexandria from? Passage:Born in Urbino, he studied at Padua and at Ferrara, where he received his doctorate in medicine. He was most famous for his central role as translator of works of ancient mathematicians. In this, his sources were primarily written in Greek and secondarily in Arabic, while his translations were primarily in Latin and secondarily in Italian. He was responsible for the publication of many treatises of Archimedes. He also translated the works of Aristarchus of Samos (On the sizes and distances of the Sun and the Moon), Pappus of Alexandria (Mathematical collection), Hero of Alexandria (Pneumatics), Ptolemy of Alexandria (Planisphere and Analemma), Apollonius of Perga (Conics) and Euclid of Alexandria (Elements). Among his pupils was Guidobaldo del Monte and Bernardino Baldi. Commandino maintained a correspondence with the astronomer Francesco Maurolico. The proposition known as Commandino's theorem first appears in his work on centers of gravity.
 Links: a. Medicine b. Apollonius of Perga c. Aristarchus of Samos d. Medicine
Example Output: c

Example Input: Question: What is the population of the city where Schchapov earned his bachelor's degree? Passage:Afanasiy Shchapov was born in the village of Anga some 210 miles from Irkutsk, into a family of a Russian sexton and Buryat woman. Educated in Irkutsk, he moved to Kazan and became a student at Kazan Theological Academy (1852–1856). Upon receiving his Bachelor's degree, Shchapov began to deliver lectures on Russian history at his alma mater (1856–1860) and later at Kazan University (1860–1861). He also studied the Solovetsky Monastery library, which had been evacuated during the Crimean War to Kazan. Fascinated with the Solovetsky Uprising, Shchapov started writing articles about the Raskol and Old Believers. On April 16, 1861, he delivered a revolutionary speech dedicated to the victims of the Bezdna Unrest, after which he was arrested and escorted to St.Petersburg. After the investigation, Shchapov was dismissed as a teacher and appointed to the Ministry of the Interior as an official in charge of the sectarian affairs. In 1862, he was discharged and placed under police surveillance.
 Links: a. Old Believers b. Bezdna unrest c. Kazan d. Old Believers
Example Output:
c