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: How deep were their heavy infantry formations normally? Passage:Having recovered from their losses at Trebia (218 BC) and Lake Trasimene (217 BC), the Romans decided to engage Hannibal at Cannae, with approximately 86,000 Roman and allied troops. They massed their heavy infantry in a deeper formation than usual, while Hannibal used the double envelopment tactic and surrounded his enemy, trapping the majority of the Roman army, who were then slaughtered. The loss of life on the Roman side was one of the most lethal single day's fighting in history; Adrian Goldsworthy equates the death toll at Cannae to "the massed slaughter of the British Army on the first day of the Somme offensive in 1916." Only about 15,000 Romans, most of whom were from the garrisons of the camps and had not taken part in the battle, escaped death. Following the defeat, Capua and several other Italian city-states defected from the Roman Republic to Carthage.
 Links: a. Cannae b. Adrian Goldsworthy c. Heavy infantry d. City-state
Example Output: c

Example Input: Question: What band(s) the artist whose song "Chamakay" Polachek contributed vocals belong to? Passage:In 2010, she joined Jorge Elbrecht of Brooklyn-based Violens to record a "sgin" of Justin Bieber's "Never Let You Go": "We went on YouTube to find a video among the highest ranks of hits, and came across 'Never Let You Go'. We went on to make what we call a 'sgin' (anagram of the word 'sing')—an original song written specifically to synch into someone else's video on mute". Caroline shot and directed video for Violens' "It Couldn't Be Perceived". Polachek and Elbrecht collaborated again in 2014 on two singles, "I.V. Aided Dreams (feat. Caroline Polachek)" and "Full Mental Erase (feat. Caroline Polachek)". In 2012, she sang with Ice Choir (solo project of Kurt Feldman of The Pains of Being Pure at Heart) on the song "Everything Is Spoilt by Use" and directed/edited its official video. Caroline contributed vocals to Blood Orange's "Chamakay" (2013), collaborating with Blood Orange again on "Holy Will" (2018). In late 2013, Polachek wrote and produced "No Angel", which was featured on Beyoncé's critically acclaimed fifth studio album, Beyoncé. Thanks to this song, at the 57th Annual Grammy Awards, she received a Grammy Award nomination for Album of the Year. Polachek then collaborated with PC Music's, Danny L Harle in early 2016 on the single "Ashes of Love". Polachek collaborated with felicita throughout his album "Hej!" (PC Music 2018) including an arrangement of the Polish traditional song "Byl Sobie Krol" (released under the title "Marzipan"), and with Charli XCX on Pop 2 (2017) on tracks "Tears (feat. Caroline Polachek)" and "Delicious (feat. Tommy Cash).
 Links: a. Danny L Harle b. Dev Hynes c. Beyoncé (album) d. Charli XCX
Example Output: b

Example Input: Question: How long after the start of the First Sino-Japanese War did the Battle of the Yalu River take place? Passage:As an ensign, Ogasawara served in combat during the First Sino-Japanese War on the cruiser Takachiho at the Battle of the Yalu River. He was subsequently served on the Amagi before transferred to the Navy General Staff Records Department, and assigned to compile an official record of naval operations during the war (which was published in 1903). Ogasawara continued to serve on the General Staff as a naval intelligence officer through the Russo-Japanese War and World War I, rising to the rank of vice admiral by 1918, aside from a one-year tour of sea duty as executive officer of the Chiyoda in 1903, and as captain of the cruiser Tokiwa and battleship Katori in 1912. He was an expert on codes and ciphers, but by the time he had reached flag rank, he was best known as public relations expert for the navy, with his colorful writings on naval history earning him the nickname of the "literary admiral".
 Links: a. Executive officer b. Russo-Japanese War c. Japanese battleship Katori d. First Sino-Japanese War
Example Output:
d