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 old was Beloff's husband when he died? Passage:Anne Beloff was born in 1921 in Hampstead to Simon Beloff and Marie Katzin. Her parents were of Russian–Jewish background, and her siblings included the historian Max Beloff, Baron Beloff, the psychologist John Beloff, the journalist Nora Beloff, and the politician Renee Soskin. She earned a degree in chemistry from University College London in 1942 before completing a PhD in the biochemistry of skin burns with Rudolph Peters at the University of Oxford. She visited Harvard Medical School in 1946 to perform research and returned to the UK in 1948. In the same year she married Ernst Boris Chain, a biochemist who had won the Nobel Prize in Physiology or Medicine in 1945, and moved with him to Rome.
 Links: a. Harvard Medical School b. Ernst Chain c. University of Oxford d. Hampstead
Example Output: b

Example Input: Question: When was the author of JFK and the Unspeakable born? Passage:Jim Garrison said anti-Communist and anti-Castro extremists in the CIA plotted the assassination of Kennedy to maintain tension with the Soviet Union and Cuba, and to prevent a United States withdrawal from Vietnam. James Douglass wrote in JFK and the Unspeakable that the CIA, acting upon the orders of conspirators with the "military industrial complex", killed Kennedy and in the process set up Lee Harvey Oswald as a patsy. Like Garrison, Douglass stated that Kennedy was killed because he was turning away from the Cold War and pursuing paths of nuclear disarmament, rapprochement with Fidel Castro, and withdrawal from the war in Vietnam. Mark Lane — author of Rush to Judgment and Plausible Denial and the attorney who defended Liberty Lobby against a defamation suit brought by former CIA agent E. Howard Hunt — has been described as a leading proponent of the theory that the CIA was responsible for the assassination of Kennedy. Others who believe the CIA was involved include authors Anthony Summers and John M. Newman.
 Links: a. Vietnam War b. Vietnam War c. James W. Douglass d. Lee Harvey Oswald
Example Output: c

Example Input: Question: Who was the author of Holy Cross Sermons? Passage:The first recorded sentence in the Polish language reads: "Day ut ia pobrusa, a ti poziwai" ("Let me grind, and you take a rest") — a paraphrase of the Latin "Sine, ut ego etiam molam." The work, in which this phrase appeared, reflects the culture of early Poland. The sentence was written within the Latin language chronicle Liber fundationis from between 1269 and 1273, a history of the Cistercian monastery in Henryków, Silesia. It was recorded by an abbot known simply as Piotr (Peter), referring to an event almost a hundred years earlier. The sentence was supposedly uttered by a Bohemian settler, Bogwal ("Bogwalus Boemus"), a subject of Bolesław the Tall, expressing compassion for his own wife who "very often stood grinding by the quern-stone." Most notable early medieval Polish works in Latin and the Old Polish language include the oldest extant manuscript of fine prose in the Polish language entitled the Holy Cross Sermons, as well as the earliest Polish-language Bible of Queen Zofia and the Chronicle of Janko of Czarnków from the 14th century, not to mention the Puławy Psalter.
 Links: a. Cistercians b. Holy Cross Sermons c. Quern-stone d. Polish language
Example Output:
b