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: In what year was CIA pilot Francis Gary Powers born? Passage:Strategic Air Command was formed by the United States Air Force after World War II to provide an active defense against any surprise attack by the Soviet Union. Though it had been an ally against Germany and Japan during World War II, by 1948 the Soviet Union showed a propensity to instigate problems with Britain, France and the United States. In August 1949, the Soviet Union detonated its first nuclear weapon and by the early 1950s had detonated a hydrogen bomb. The war of words between the two superpowers escalated during 1950s and 1960s into a nuclear arms race. By 1970 the United States was using a "Triad Defense System" composed of nuclear submarines armed with nuclear missiles, land based intercontinental ballistic missiles with nuclear warheads and bombers capable of delivering hydrogen bombs on enemy targets. The Boeing B-52 Stratofortress bomber had been designed in the early 1950s by Boeing Aircraft Company to give the United States Air Force the capability of delivering nuclear weapons far inside the territory of Soviet Russia. The planes were to fly at high altitude with enough fuel to hit their target. In May 1960, the Soviet Union made known its capability to shoot such high altitude planes out of the sky by using a surface to air missile to strike CIA pilot Francis Gary Powers' U-2 spy plane over Russian territory. From that point on, the high-altitude B-52 had to be modified to conduct missions at low level, something it was not intended to be.
 Links: a. Strategic Air Command b. Intercontinental ballistic missile c. Intercontinental ballistic missile d. Francis Gary Powers
Example Output: d

Example Input: Question: How many total teams participated in the cup the team won in 2017? Passage:From their foundation, the team primarily played five, seven and eleven-a-side exhibition matches, which were filmed and uploaded to their YouTube channel. By September 2016, the team's Instagram account had over 100,000 followers, their Twitter account 41,000, and a 'penalty challenge' video uploaded to YouTube had accumulated over one million views. Hashtag United played various teams including a Comedians XI whom they beat 19–1, Google, the GB Deaf Team, Barawa and a Manchester City staff team, with opponents fielding former professional footballers such as Paul Dickov, Graeme Le Saux and Ray Parlour, and celebrities including Omid Djalili. At one point in 2016, the club was close to signing professional footballer Adebayo Akinfenwa. In 2017 the club won the EE Wembley Cup, a competition that Spencer FC had won in 2015 and 2016; the team included Scott Pollock, who went on to sign professional terms with Northampton Town. 
 Links: a. Graeme Le Saux b. EE Wembley Cup c. Exhibition game d. Twitter
Example Output: b

Example Input: Question: Why was James Baskett unavailable to play Br'er Fox in Song of the South? Passage:Walt Disney engaged O'Malley to provide voices for animated films such as the Cockney coster in the "Supercalifragilisticexpialidocious" sequence in Mary Poppins (1964); Cyril Proudbottom, Winkie, and a policeman in The Adventures of Ichabod and Mr. Toad (1949); and the role of Colonel Hathi and the vulture Buzzie in The Jungle Book (1967). His voice can be heard in Alice in Wonderland (1951), in which he performs all the character voices in "The Walrus and the Carpenter" segment (besides Alice), including Tweedledum and Tweedledee, the Walrus, the Carpenter, and Mother Oyster. O'Malley also provided the voice of Br'er Fox in Song of the South (1946) when James Baskett was unavailable. Actor Dick Van Dyke has said that O'Malley was his dialect coach on Mary Poppins, attributing his infamous Cockney accent in that film to O'Malley.
 Links: a. Dick Van Dyke b. Mary Poppins (film) c. Song of the South d. The Jungle Book (1967 film)
Example Output:
c