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 was the leader of Solidarity in 1991? Passage:The 1991 Polish parliamentary election was held on 27 October 1991 to elect deputies to both houses of the National Assembly. The 1991 election was notable on several counts. It was the first parliamentary election to be held since the formation of the Third Republic, the first entirely free and competitive legislative election since the fall of communism, the first completely free legislative election of any sort since 1928, and only the fifth completely free election in all of Polish history. Due to the collapse of the Solidarity movement's political wing, the 1991 election saw deep political fragmentation, with a multitude of new parties and alliances emerging in its wake. Low voting thresholds within individual constituencies, along with a five percent national threshold allocated to a small portion of the Sejm, additionally contributed to party fragmentation. As a result, 29 political parties gained entry into the Sejm and 22 in the Senate, with no party holding a decisive majority. Two months of intense coalition negotiations followed, with Jan Olszewski of the Centre Agreement forming a minority government along with the Christian National Union, remnants of the broader Center Civic Alliance, and the Peasants' Agreement, with conditional support from Polish People's Party, Solidarity and other minor parties.
 Links: a. Solidarity (Polish trade union) b. Solidarity (Polish trade union) c. Jan Olszewski d. Centre Agreement
Example Output: a

Example Input: Question: What country are these cities part of? Passage:Following its involvement in The Troop, FujiFilm commissioned Glory Film Co. to make a series of films to demonstrate its new motion picture filmstocks. For these projects Glory employed leading cinematographers: Oscar-winners Jack Cardiff OBE, BSC, ASC, (The African Queen) and Ronnie Taylor BSC (Gandhi) together with Phedon Papamichael ASC (Walk the Line), John de Borman BSC (The Full Monty), Sue Gibson BSC (Spooks), Thierry Arbogast AFC (The Fifth Element), Ron Stanett CSC (Evel Knievel) and Tony Pierce-Roberts BSC (A Room With a View). The films were shot at Pinewood (LightsII) and Shepperton studios (Lights II, Return of The Shadow), with locations including Hastings in East Sussex (The Glow). 'Lights II' (2005) featured the last cinema performance of John Mills (at age 96). He played a tramp and was photographed by cinematographer Jack Cardiff, himself 90 years old.
 Links: a. Phedon Papamichael b. Hastings c. Jack Cardiff d. Jack Cardiff
Example Output: b

Example Input: Question: When did the war begin that prompted the Navy to build the airport? Passage:In 1950, Admiral Arthur W. Radford, Commander-in-Chief of the United States Pacific Fleet, envisioned an naval base in the Western Pacific to enhance Seventh Fleet capabilities. The Korean War began and the Navy realized it had a need for an air station in the region. Cubi Point in the Philippines was selected, and civilian contractors were initially approached for the project. After seeing the Zambales Mountains and the surrounding jungle, they claimed it could not be done. The U.S. Navy then turned to the Seabees and was told no problem, Can do. The first Seabees to arrive were surveyors of Construction Battalion Detachment 1802. Moblie Comstruction Battalion 3 arrived on 2 October 1951 to get the project going and was joined by MCB 5 in November. Over the next five years, MCBs 2, 7, 9, 11 and CBD 1803 also contributed to the effort. They leveled a mountain to make way for a nearly runway. NAS Cubi Point turned out to be one of the largest earth-moving projects in the world, equivalent to the construction of the Panama Canal. Seabees there moved of dry fill plus another 15 million that was hydraulic fill. The $100 million facility was commissioned on 25 July 1956, and comprised an air station with an adjacent pier capable of docking the Navy's largest carriers. Adjusted-for-inflation, today's price-tag for what the Seabees built at Cubi Point would be $906,871,323.53. After decades of use by American forces, Mount Pinatubo erupted in 1991, burying Cubi Point in 18-36 inches of ash. Despite this, the American government wished to keep the Subic Naval Base and signed a treaty with the Philippine government. The treaty was not ratified, however, failing by a slim margin in the Philippine Senate. Attempts to negotiate a new treaty were soon abandoned and the United States was informed that it was to withdraw within one year. U.S. forces withdrew in November 1992, turning over the facility with its airport to the Philippine government.
 Links: a. United States Seventh Fleet b. Korean War c. Panama Canal d. Senate of the Philippines
Example Output:
b