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: Which Nobel Laureate had published more papers by the year Barschall emigrated to the US, Fritz Haber or Emil Fischer? 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. Fritz Haber b. Jews c. Nuclear fission d. Emil Fischer
Example Output: d

Example Input: Question: How wide is the body of water that separates the Eurasian and North American continents? Passage:The Russian Empire began its interest of the Pacific Northwest in the 18th century, initially curious if there was a land connection between the Eurasian and North American Continents. Two expeditions were led by Vitus Bering, with the findings proving the separation of two continents through the Bering Sea. Being the first European nation to chart much of what comprises the modern American state of Alaska, many locations retain Russian place names. The discovery of sizable fur bearing populations by Bering drew the attention of promyshlenniki previously engaged in the Siberian fur trade. Based out of the Siberian ports of Okhotsk or Petropavlovsk, fur trappers sailed and reported the location of land formations like the Aleutian Islands, Kodiak Island and portions of the Alaskan mainland. Relations with Native Alaskans was often terse due to the uncontrolled actions of particular promyshlenniki who killed and raped Indigenous on islands they trapped furs.
Links: a. Bering Sea b. Siberia c. Russian Empire d. Bering Sea
Example Output: a

Example Input: Question: What happened to the building that spanned 8 or 9 acres? Passage:William Briwere was granted the lordship of the Manor of Bridgwater by John of England in 1201, and founded Bridgwater Friary. Through Briwere's influence, King John granted three charters in 1200; for the construction of Bridgwater Castle, for the creation of a borough, and for a market. Bridgwater Castle was a substantial structure built in Old Red Sandstone, covering a site of 8 or 9acres (32,000 to 36,000m). A tidal moat, up to wide in places, flowed about along the line of the modern thoroughfares of Fore Street and Castle Moat, and between Northgate and Chandos Street. The main entrance opposite the Cornhill was built with a pair of adjacent gates and drawbridges. In addition to a keep, located at the south-east corner of what is now King Square, documents show that the complex included a dungeon, chapel, stables and a bell tower. Built on the only raised ground in the town, the castle controlled the crossing of the town bridge. A thick portion of the castle wall and water gate can still be seen on West Quay, and the remains of a wall of a building that was probably built within the castle can be viewed in Queen Street. The foundations of the tower forming the north-east corner of the castle are buried beneath Homecastle House. William Briwere also founded St John's hospital which, by the time of the Dissolution of the Monasteries under Henry VIII, was worth the substantial sum of almost 121 pounds, as well as starting the construction of the town's first stone bridge. William Briwere also went on to found the Franciscan Bridgwater Friary in the town.
Links: a. Borough b. Bell tower c. Bridgwater Castle d. Drawbridge
Example Output:
c