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 soldiers died in the battle that Stanley missed due to illness? Passage:He fought at several battles in Missouri, including the Battle of Wilson's Creek, where he guarded the supply trains. President Abraham Lincoln appointed Stanley as brigadier general September 28, 1861, although the U.S. Senate did not confirm the appointment until March 7, 1862. Fighting in the Western Theater, he participated in the operations against New Madrid, Missouri and the Battle of Island Number Ten. He was involved in numerous major battles, including the Second Battle of Corinth, where he commanded a division of infantry of the Army of the Mississippi, and the Battle of Stones River, in which he led the cavalry of the Army of the Cumberland. On March 11, 1863, Stanley was appointed major general to rank from November 29, 1862. Stanley also led the Union cavalry in the Tullahoma Campaign. He fell ill late in 1863 and missed the Battle of Chickamauga. In 1864, he fought under William Tecumseh Sherman as a division commander in the IV Corps of the Army of the Cumberland during the Atlanta Campaign, and he was promoted to command of the corps when Maj. Gen. Oliver O. Howard was named commander of the Army of the Tennessee. After the capture of the city, instead of employing him marching to the sea, Sherman dispatched Stanley and his IV Corps to Tennessee to help protect the state from invasion by John Bell Hood's Army of Tennessee.
 Links: a. Army of Tennessee b. Missouri c. Battle of Chickamauga d. John Bell Hood

Ex Output:
c


Ex Input:
Question: Which episode with Malohkeh had the highest ratings? 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. Richard Hope (actor) b. The Hungry Earth c. Mitchell and Webb d. Harry Potter (film series)

Ex Output:
b


Ex Input:
Question: How old was Mahut when he started playing professional tennis? Passage:John Robert Isner (born April 26, 1985) is an American professional tennis player who has been ranked as high as No. 8 in men's singles by the Association of Tennis Professionals (ATP). Considered one of the best servers ever to play on the ATP World Tour, Isner achieved his career-high singles ranking in July 2018 by virtue of his maiden Masters 1000 crown at the 2018 Miami Open and a semifinals appearance at the 2018 Wimbledon Championships. He has also twice reached the quarterfinals at the US Open in 2011 and 2018, the latter of which helped qualify him for his first ATP Finals appearance later that year. He currently has the second-most aces in the history of the ATP World Tour, having served 11,969 aces. At the 2010 Wimbledon Championships, he played the longest professional tennis match in history, defeating Nicolas Mahut in a total of 11 hours and 5 minutes, played over the course of three days.
 Links: a. Association of Tennis Professionals b. ATP Finals c. ATP Finals d. Nicolas Mahut

Ex Output:

d