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: How many pieces had Beethoven composed before the one Pinza performed in 1935? Passage:Pinza sang once again under the baton of Toscanini in 1935, this time with the New York Philharmonic Orchestra, as the bass soloist in performances of Beethoven's Missa Solemnis. One of these performances was broadcast by CBS and preserved on transcription discs; this recording has been issued on LPs and CDs. He also sang in Toscanini's February 6, 1938, NBC Symphony Orchestra's broadcast performance of Beethoven's Ninth Symphony. These performances both took place in Carnegie Hall. In March 1942, Pinza was arrested at his home and unjustly detained 3 months on Ellis Island with hundreds of other Italian-Americans who were suspected of supporting the Axis. The incident was extremely traumatic for Pinza, and he suffered from severe depression for years afterward. In October 1947, he performed the role of Méphistophélès in Guonod's Faust opposite his daughter, soprano Claudia Pinza Bozzolla, as Marguerite at the San Francisco Opera.
 Links: a. Symphony No. 9 (Beethoven) b. Missa solemnis (Beethoven) c. Faust (opera) d. San Francisco Opera
Example Output: b

Example Input: Question: Which of the seas that the Sibiryakov sailed to was larger? Passage:A. Sibiryakov sailed on 28 June 1932 from the Krasny (previously Sobornoy) docks in Arkhangelsk, crossed the Kara Sea and chose a northern, unexplored way around Severnaya Zemlya to the Laptev Sea. In September, after calling at Tiksi and the mouth of the Kolyma, the propeller shaft broke and the icebreaker drifted for 11 days. However, A. Sibiryakov crossed the Chukchi Sea using improvised sails and arrived in the Bering Strait in October. A. Sibiryakov reached the Japanese port of Yokohama after 65 days, having covered more than in the Arctic seas. This was regarded as a heroic feat of Soviet polar seamen and Chief of Expedition Otto Schmidt and Captain Vladimir Voronin were received with many honors at their return to Russia.
 Links: a. Arkhangelsk b. Tiksi c. Kara Sea d. Kolyma
Example Output: c

Example Input: Question: Which network has aired Teletubbies the longest? Passage:Teletubbies has been aired in over 120 countries in 45 different languages. In the United States, the series airs on Nickelodeon as part of the Nick Jr. block. Episodes are also released through the Nick Jr. mobile application and on-demand services. The original series is available as part of the Noggin subscription service in North America. It had aired on PBS Kids from 6 April 1998 to 29 August 2008. BBC Worldwide channels carry the series in most of Africa, Asia and Poland. A Spanish dub airs on Clan in Spain. In Greece, the series airs on Nickelodeon Greece. NPO Zappelin carries the show in the Netherlands and MTVA airs it in Hungary. In Australia and New Zealand, the series airs on CBeebies Australia and ABC Kids. JimJam's Benelux feed airs the series and Ultra airs it in Serbia. Teletubbies also airs on SIC in Portugal and e-Junior in the Middle East.
 Links: a. Nickelodeon b. Noggin (brand) c. Sociedade Independente de Comunicação d. Nick Jr. (TV programming block)
Example Output:
a