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: Who won the World Cup where the Costa Rican team had a prominent performance? Passage:Since the late 1980s, the team has continuously been visible as a solidly competitive side, with a prominent performance in the 1990 FIFA World Cup in Italy, making it to the knockout stage in their debut after finishing second in their group during the first phase, below Brazil. They also managed to qualify for the 2002 and 2006 FIFA World Cups. In 2014, Costa Rica made their best performance in history by finishing first in their group that consisted of three former World Cup champions: Uruguay, Italy, and England. During the Round of 16 they defeated Greece 5–3 via a penalty shootout after a 1–1 draw. Moreover, during the match against a much better team, Navas saved more than 15 shots due to the Costa Rican very weak defense. The match was characterized as "Navas vs Greece". They reached the quarterfinals for the very first time as the Ticos were defeated by the Netherlands also in a penalty shootout (3–4) after a scoreless draw on 5 July. Their 2018 World Cup campaign ended in a 4th place group stage exit with their only point coming from a 2-2 draw vs Switzerland.
 Links: a. 2006 FIFA World Cup b. 1990 FIFA World Cup c. 2006 FIFA World Cup d. Keylor Navas
Example Output: b

Example Input: Question: Who did the 197th fight against in the Battle for Caen? Passage:After spending many years training in the United Kingdom the 197th Brigade, together with the rest of the 59th Division, landed in France on 29 June 1944, D-Day + 23. The division, under command of XII Corps, became part of the British Second Army, which was engaged in the Battle for Caen. With the arrival of the 59th Division General Bernard Montgomery, commanding the Anglo-Canadian 21st Army Group, decided to renew the offensive to capture the city of Caen, which was originally a D-Day objective for the British 3rd Infantry Division which ultimately failed, due mainly to heavier resistance than expected. Operation Charnwood. The brigade's first action was Operation Charnwood with 2/6th South Staffords (of 177th Brigade), along with C Company of the 7th Battalion, Royal Northumberland Fusiliers (the divisional MG Battalion), together with numerous units of the Royal Artillery under command (and 510 Field Company, RE), and supported by the Churchill tanks of the 1st East Riding Yeomanry (of 27th Armoured Brigade). The brigade suffered comparatively light casualties in Charnwood. The 197th Brigade later fought in the Second Battle of the Odon, and the Battle of the Falaise Gap.
 Links: a. Battle for Caen b. Bernard Montgomery c. General (United Kingdom) d. 21st Army Group
Example Output: a

Example Input: Question: Where was Lake Minchin located? Passage:Lake Minchin was a saltwater lake, which covered the basins of the Salar de Uyuni, Salar de Coipasa, Lake Poopo and Salar de Empexa, including the towns of Llica, Oruro and the Desaguadero River valley. The lake had an extension of in east-west direction and of in north-south direction. A sill at Ulloma separated Lake Minchin from Lake Titicaca. Water levels reached an altitude of above sea level, indicating a depth of above the Uyuni basin. In the Poopo basin, water levels may have reached . At Cerro Lipillipi terraces between are dated between 25,700 and 31,750 BP. Another estimate is . Earlier estimates of the altitude are , resulting in depths of . Such water heights exceed these of preceding lakes, and together with even higher water levels of the subsequent Lake Tauca they are part of a trend of increasing water levels in the southern Altiplano which contrasts with progressively decreasing lake levels in the northern Altiplano. Earlier research suggested an opposite trend of lowering water levels in both basins. The surface area of Lake Minchin may have been , or . A lake terrace at is also attributed to Lake Minchin. The highest lake terraces at and were later found to belong to Lake Tauca, making it the deeper of the two lakes. If Minchin reached a water level of it may have spilled into the Pilcomayo River, draining from there via the Rio de la Plata into the Atlantic Ocean. It is also possible that the lake temporarily drained into the Pacific Ocean through its southwesternmost sector at Salar de Ascotán; such an outlet would have existed for only a brief time, however, before it was obstructed by volcanism. San Agustin, San Cristobal and Colcha formed islands in the lake, which was separated into a Coipasa half and an Uyuni half by a peninsula of the Serranía Intersalar; straits at Llica and Salinas de Garci Mendoza connected the two halves. Bays developed close to Isluga, Empexa and Ollagüe.
 Links: a. Lake Poopó b. Oruro, Bolivia c. Salar de Uyuni d. Río de la Plata
Example Output:
c