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: When was the man whose name is used as the unit of radio wave frequency born? Passage:A modulated radio wave, carrying an information signal, occupies a range of frequencies. See diagram. The information (modulation) in a radio signal is usually concentrated in narrow frequency bands called sidebands (SB) just above and below the carrier frequency. The width in hertz of the frequency range that the radio signal occupies, the highest frequency minus the lowest frequency, is called its bandwidth (BW). A given amount of bandwidth can carry the same amount of information (data rate in bits per second) regardless of where in the radio frequency spectrum it is located, so bandwidth is a measure of information-carrying capacity. The bandwidth required by a radio transmission depends on the data rate of the information (modulation signal) being sent, and the spectral efficiency of the modulation method used; how much data it can transmit in each kilohertz of bandwidth. Different types of information signals carried by radio have different data rates. For example, a television (video) signal has a greater data rate than an audio signal.
Links: a. Data signaling rate b. Carrier wave c. Hertz d. Audio signal
Example Output: c

Example Input: Question: How old was the king when he awarded Mairi and Knocker the Order of Leopold II, Knights Cross? Passage:Chisholm and Knocker soon came to the conclusion that they could save more lives by treating the wounded directly on the front lines. In November, they decided to leave the corps and set up their own dressing station five miles east in a town named Pervyse, north of Ypres, just one hundred yards from the trenches. Here, in a vacant cellar which they named "Poste de Secours Anglais" ("British First Aid Post"), the two would spend the next three and a half years tending to the wounded. No longer affiliated with the Belgian Red Cross, they began acting completely as free agents and had to support their work by raising their own funds. Through sheer perseverance Knocker was able to arrange for the two of them to be officially seconded to the Belgian garrison stationed there. In January 1915, they were both decorated by King Albert I of Belgium with the Order of Leopold II, Knights Cross (with palm) for their courageous work on the front lines. They were also awarded the British Military Medal and both made Officers of the Most Venerable Order of St. John of Jerusalem. Chisholm was also decorated with the Queen Elisabeth Medal of Belgium and the British campaign medals, including the 1914 Star. The two became instant celebrities earning the distinction of being among the most photographed women of the war.
Links: a. Ypres b. Albert I of Belgium c. Queen Elisabeth Medal d. Pervijze
Example Output: b

Example Input: Question: How old was the player who signed with Sunderland on September 8th, at the time of the signing? Passage:Sunderland opened the month with a 10 defeat away to Manchester United on 1 September, Louis Saha scored the winner 18minutes from full-time. Roy Keane said "I'm delighted with the overall performance. It would have been nice to test their goalkeeper a bit more but overall I'm delighted with the players' efforts." about the team's display. Jack Pelter signed for Sunderland on 8 September, from New Zealand team Canterbury United, on a free transfer in an original one-month deal. Two weeks after the defeat to Manchester United, Sunderland beat Reading 21 on 15 September. Kenwyne Jones and Ross Wallace scored the Sunderland goals in a game which was overshadowed by the tribute paid to 1973 FA Cup Final scorer Ian Porterfield who died on 11 September 2007. Sunderland met Middlesbrough on 22 September in their first north east derby of the season. Grant Leadbitter scored in the 2nd minute to put Sunderland in front, but two ex-Sunderland players; Julio Arca and Stewart Downing put Middlesbrough into the lead. Liam Miller scored an 89th minute volley to save a point for Sunderland. Grant Leadbitter scored his second goal in as many games on 29 September as Blackburn Rovers beat Sunderland 21.
Links: a. Jack Pelter b. Jack Pelter c. 1973 FA Cup Final d. Julio Arca
Example Output:
a