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: Who was in charge at Princeton University the year Barschall graduated from that school? Passage:Barschall was born as Heinrich Hermann Barschall in Berlin, Germany; his father was a patent attorney who had received a Ph.D. in chemistry after studying with Nobel Laureates Emil Fischer and Fritz Haber. After beginning study in several universities in Germany, he emigrated to the United States in 1937 during the early Holocaust period; though raised as a Lutheran, he had some Jewish ancestry. He received his Ph.D. from Princeton University in 1940 under the direction of Rudolf Ladenburg; he also worked closely with John A. Wheeler. After a suggestion by Niels Bohr, he carried out in only a few days with fellow graduate student Morton H. Kanner the first demonstration of fission by fast neutrons and thorium and uranium. His thesis was on the interaction of fast neutrons with helium. In a paper with John A. Wheeler he reported the discovery of spin-orbit coupling in neutron scattering.
Links: a. Emil Fischer b. Princeton University c. Jews d. John Archibald Wheeler

Ex Output:
b

Ex Input:
Question: How many people attended the conference held near Berlin in January 1942? Passage:Following the invasion of Poland in 1939 most of the 3.5 million Polish Jews were rounded up and put into newly established ghettos by Nazi Germany. The system was intended to isolate the Jews from the outside world in order to facilitate their exploitation and abuse. The supply of food was inadequate, living conditions were cramped and unsanitary, and the Jews had no way to earn money. Malnutrition and lack of medicine led to soaring mortality rates. In 1941, the initial victories of the Wehrmacht over the Soviet Union inspired plans for the German colonisation of occupied Poland, including all territory within the new district of General Government. At the Wannsee Conference held near Berlin on 20 January 1942, new plans were outlined for the genocide of the Jews, known as the "Final Solution" to the Jewish Question. The extermination programme was codenamed Aktion Reinhard in German, to differentiate it from the Einsatzgruppen mass killing operations in territories conquered by Nazi Germany, in which half a million Jews had already been annihilated.
Links: a. Einsatzgruppen b. Wannsee Conference c. Operation Reinhard d. General Government

Ex Output:
b

Ex Input:
Question: Which of the organizations that are represented on YBF's advisory board has the highest membership numbers? Passage:As of September 2010, YBF's "advisory board" includes Matthew Elliott, founder of the UK TaxPayers' Alliance, and representatives of the Heritage Foundation (a US conservative thinktank), US Competitive Enterprise Institute and American Conservative Union (a US conservative lobbying organisation). It also includes the founder of the US Leadership Institute, the President of the US Jesse Helms Center, the President of the Young America's Foundation, the co-founder of the US Henry Jackson Society and a former Executive Director of the Collegiate Network. British representatives include Professor Patrick Minford, blogger Iain Dale (who resigned in the same year) and two local councillors. Liam Fox, the shadow defence secretary, was a member of the YBF's parliamentary council. Conor Burns was until shortly before becoming an MP in 2010 the vice-president of YBF.
Links: a. Iain Dale b. Collegiate Network c. TaxPayers' Alliance d. Conor Burns

Ex Output:
c