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: Who won the second race that Sebastian Vettel participated in? Passage:Driving in place of Robert Kubica, Vettel made his début in with BMW Sauber in the United States Grand Prix; making him (at that time) the youngest points scorer in Formula One by finishing eighth in the race. His second race came with Scuderia Toro Rosso in the 2007 Hungarian Grand Prix and he stayed at Toro Rosso until the end of the season. Vettel won his first race at the 2008 Italian Grand Prix starting from his first pole, which remains Toro Rosso's only win. He then moved to Red Bull for the season and stayed at Red Bull until the end of the season. During his six years at Red Bull, he secured four championships, 38 wins, 44 pole positions and 65 podium finishes. Vettel's first championship came at the age of 23 years and 134 days in , becoming the youngest ever world champion; this was followed by three consecutive championships. , a winless season for Vettel, was his final year with Red Bull; he then joined Scuderia Ferrari. In his first year with Ferrari, he secured 3 wins, 1 pole position, and 13 podium finishes, going on to finish 3rd in the standings. In the season, Vettel had no wins with Ferrari and finished 4th in the standings. However, in he finished the season in second place with 5 victories. His Grand Prix victories is the third highest of all-time, only behind Lewis Hamilton's wins and Michael Schumacher at 91.
 Links: a. Red Bull Racing b. 2007 Hungarian Grand Prix c. Robert Kubica d. List of Formula One driver records
Example Output: b

Example Input: Question: How many years were there between the end of the British Burma Campaign and the start of the Battle of Na San? Passage:The First Indochina War had raged, as guerrilla warfare, since 19 December 1946. From 1949, it evolved into conventional warfare, due largely to aid from the communists of the People's Republic of China ("PRC") to the north. Subsequently, the French strategy of occupying small, poorly defended outposts throughout Indochina, particularly along the Vietnamese-Chinese border, started failing. Thanks to the terrain, popular support for August Revolution and support for decolonization from bordering China and the U.S.S.R., the Viet Minh had succeeded in turning a "clandestine guerrilla movement into a powerful conventional army", following asymmetric warfare theory laid by Mao Tse Tung, something which previously had never been encountered by the western colonial powers. In October 1952, fighting around the Red River Delta spread into the Thai Highlands, resulting in the Battle of Nà Sản, at which the Viet Minh were defeated. The French used the lessons learned at Nà Sản – strong ground bases, versatile air support, and a model based on the British Burma Campaign – as the basis for their new strategy. The Viet Minh, however, remained unbeatable in the highland regions of Vietnam, and the French "could not offset the fundamental disadvantages of a roadbound army facing a hill and forest army in a country which had few roads but a great many hills and forests".
 Links: a. China b. On Guerrilla Warfare c. Battle of Nà Sản d. China
Example Output: c

Example Input: Question: How old was the artist with whom Polachek collaborated  on the single "Ashes of Love"? Passage:In 2010, she joined Jorge Elbrecht of Brooklyn-based Violens to record a "sgin" of Justin Bieber's "Never Let You Go": "We went on YouTube to find a video among the highest ranks of hits, and came across 'Never Let You Go'. We went on to make what we call a 'sgin' (anagram of the word 'sing')—an original song written specifically to synch into someone else's video on mute". Caroline shot and directed video for Violens' "It Couldn't Be Perceived". Polachek and Elbrecht collaborated again in 2014 on two singles, "I.V. Aided Dreams (feat. Caroline Polachek)" and "Full Mental Erase (feat. Caroline Polachek)". In 2012, she sang with Ice Choir (solo project of Kurt Feldman of The Pains of Being Pure at Heart) on the song "Everything Is Spoilt by Use" and directed/edited its official video. Caroline contributed vocals to Blood Orange's "Chamakay" (2013), collaborating with Blood Orange again on "Holy Will" (2018). In late 2013, Polachek wrote and produced "No Angel", which was featured on Beyoncé's critically acclaimed fifth studio album, Beyoncé. Thanks to this song, at the 57th Annual Grammy Awards, she received a Grammy Award nomination for Album of the Year. Polachek then collaborated with PC Music's, Danny L Harle in early 2016 on the single "Ashes of Love". Polachek collaborated with felicita throughout his album "Hej!" (PC Music 2018) including an arrangement of the Polish traditional song "Byl Sobie Krol" (released under the title "Marzipan"), and with Charli XCX on Pop 2 (2017) on tracks "Tears (feat. Caroline Polachek)" and "Delicious (feat. Tommy Cash).
 Links: a. 57th Annual Grammy Awards b. Beyoncé (album) c. PC Music d. Danny L Harle
Example Output:
d