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.

Ex Input:
Question: How many years after Wish You Were Here was released was The Wall released? Passage:Storm Thorgerson, who had done the majority of album covers for Pink Floyd, did the Echoes art which features recursive windows in an infinite regression as a nod to his own cover for 1969's Ummagumma, and the objects on each landscape refer to the Pink Floyd discography. For instance, there's the man on fire from Wish You Were Here, another wearing the Delicate Sound of Thunder lightbulb suit, dolls of the Atom Heart Mother cow and the Animals pig, a bike and both a brick wall and the hammers from The Wall. Eventually Thorgerson opted to make two images, with another used for the back cover. To create the idea on a photograph, various walls - which had varied measurements and angles to ensure that "nothing seemed to fit other than by eye through the lens." - were built and put in a country landscape in Sussex. Actors, props and fittings were set in and between those walls. The original design was one of two sketches submitted for Dream Theater's 1997 album Falling into Infinity, with the original being framed and hanging in the home of former Dream Theater drummer Mike Portnoy and is pointed out by Portnoy in his Hudson Music instructional drum DVD In Constant Motion.
Links: a. Wish You Were Here (Pink Floyd album) b. Sussex c. Ummagumma d. Atom Heart Mother

Ex Output:
a

Ex Input:
Question: Did Blake or Philby defect first? Passage:In May 1986, Souther requested Soviet citizenship, aware that the investigation against him was progressing. In June, fearing imminent arrest, Souther defected to the Soviet Union by flying from the United States to Rome, where the Soviet intelligence services transferred him to Moscow. Initially, Soviet counterintelligence units were suspicious of Souther's defection and feared that he was a double agent for the CIA, but he was cleared shortly afterwards. On 2 October 1986, Souther was granted Soviet citizenship in a decree from the Presidium of the Supreme Soviet, and adopted the Russian name Mikhail Yevgenyevich Orlov. Souther was well-received by the Soviet authorities, gifting him an apartment in Moscow and a dacha on the outskirts of the city, and promoting him to the rank of major in the KGB one of few foreign spies to be commissioned as an officer in the agency. Souther became actively engaged in scientific activities, developed his own English teaching program, walked around Moscow a lot, and travelled to other Soviet cities. Souther met and befriended other foreign Soviet intelligence agents that had defected including Kim Philby and George Blake. Souther married a Russian woman named Elena, an English teacher at the Intelligence Institute, and they had a daughter named Alexandra. In early 1989, Souther was awarded an Order of Friendship of Peoples for his contributions in the intelligence services following a petition from the KGB leadership.
Links: a. George Blake b. George Blake c. Dacha d. Major

Ex Output:
a

Ex Input:
Question: Who filled the prior titular character preceding the one featured in The Eternal Summer? Passage:Chibnall suggested including a "bonkers" gang of characters picked from around time and space. He felt that Doctor Who could have "collisions of characters that no other show in the world can do", and that it was about finding a "disparate" group of characters who would "bounce" off each other. Nefertiti's decision not to return to her own time fits in with the historical record, as the date and cause of her death are unknown. Chibnall asked to introduce Rory's father, as Amy and Rory would be leaving in four episodes and Rory's family life had not been explored yet. Mark Williams who played Rory's father previously appeared in the Fifth Doctor audio adventure The Eternal Summer. Rupert Graves, who played an Edwardian hunter in this episode, previously worked with Moffat on the BBC series Sherlock. David Bradley's character, Solomon, was modelled on a "well-known nightclub owner with long hair". Chibnall described him as "half businessman, half Somali pirate". Bradley and Williams had previously worked together on the Harry Potter film franchise. Bradley was later cast as the First Doctor William Hartnell for the 50th anniversary documentary drama An Adventure in Space and Time. Comedy duo Mitchell and Webb provided the voices of Solomon's two robots; executive producer Caroline Skinner called the casting choice "perfect". Richard Hope, who played the Silurian Bleytal, previously appeared as Malohkeh in the episodes "The Hungry Earth", "Cold Blood" and "The Wedding of River Song".
Links: a. David Bradley (English actor) b. Somalis c. Fifth Doctor d. David Bradley (English actor)

Ex Output:
c