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 miles long is the river that Silvanus drove the Alamanni tribesmen back from? Passage:Silvanus was born in Gaul, the son of Bonitus, a Laetic Frankish general who had supported Constantine I in the civil war against Licinius. Like so many other Franks of his times, and like his father before him, he was a loyal and thoroughly romanized "barbarian" in the military service of the Empire. By AD 351, he held the rank of tribune and was one of the senior officers who defected to Emperor Constantius II at the Battle of Mursa Major, after initially supporting the usurper Magnentius. An able soldier, Silvanus was eventually promoted to the rank of Magister militum per Gallias, a crucial post, then in AD 352-353, Constantius personally entrusted him with the difficult task of driving the Alamanni tribesmen raiding and looting in Gaul back beyond the Rhine, and restoring the fast eroding Roman authority in the province. This Silvanus fulfilled partly by bribing the Alamanni chieftains with the taxes he had collected, partly by defeating the Alamanni in battle and partly by suppressing the local bagaudae insurrections flaring up again in central and northern Gaul.
 Links: a. Bonitus (magister militum) b. Constantine the Great c. Rhine d. Rhine
Example Output: c

Example Input: Question: How old was the Liberal Unionist MP when he died? Passage:Morton first stood for Parliament at the 1885 general election, when he contested Hythe, and was unsuccessful again in Christchurch at the 1886 election. He won a seat three years later, when he was elected at a by-election in October 1889 as the Member of Parliament (MP) for Peterborough, after the death of the Liberal Unionist MP John Wentworth-FitzWilliam, becoming the 81st new MP since the general election in 1886. His victory was unexpected, and when the result was declared he said that he hoped his victory would be seen as a gesture of conciliation Ireland. He was re-elected in 1892, and raised in Parliament the issue of the appointment of Justices of the Peace (magistrates) in April 1893. In November that year, 280 Gladstonian MPs met the Lord Chancellor, Lord Herschell, in the House of Lords to discuss the system. Morton led the response to the Lord Chancellor's explanation and defence of the existing system of appointment, and denounced the reliance on advice from Lord Lieutenants who were entirely dependent on what Morton called "class cliques". He was also a member of a Select Committee set up to examine the accommodation provided for members and officials of the House of Commons. Great Western Railway
 Links: a. Great Western Railway b. Parliament of the United Kingdom c. John Wentworth-FitzWilliam d. Hythe (UK Parliament constituency)
Example Output: c

Example Input: Question: Which organization did Wayne serve as chairman longer? Passage:Roycroft was born in 1946 as the second of three sons to Bill Roycroft, an Olympic equestrian gold medallist, and his wife, Mavis. He won bronze medals in team eventing at the 1968 Mexico City and 1976 Montreal Olympics, competing alongside his father at both the games. He was selected for the 1980 Moscow Olympics but was affected by the boycott of the games. He was the Australian flag bearer at the 1984 Los Angeles Olympics; his father had done the same thing 16 years previously. He coached the Australian eventing team from 1988 to 2010, taking up the role from his father. his first Olympics as a coach were the 1988 Seoul Games; under his reign the eventing team won gold medals at the 1992 Barcelona, 1996 Atlanta, and 2000 Sydney Olympics and a silver medal at the 2008 Beijing games, and Matthew Ryan won an individual gold medal in 1992 and Andrew Hoy won an individual silver medal in 2000. He was chairman of the International Federation for Equestrian Sports Eventing Committee from 2000 to 2009, and also served as chair of Equestrian New South Wales and Equestrian Australia.
 Links: a. Eventing b. 1988 Summer Olympics c. 2008 Summer Olympics d. International Federation for Equestrian Sports
Example Output:
d