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: Did the operation that Musicki contacted the Chetnik leader about actually take place? Passage:Mušicki was stationed in Slavonski Brod at the time of the Axis invasion of Yugoslavia in April 1941 and served as the Royal Yugoslav Army commander responsible for the railroad between Belgrade and Zagreb in the rank of colonel. He demonstrated his support for the Germans by helping their forces during the invasion. Yugoslavia was quickly conquered by the Axis powers and Mušicki remained in Slavonski Brod for several months after the conquest. He attempted to join the Ustaše Militia there, but was rejected. He went to Belgrade in mid-August, where he was received by Zbor leader Dimitrije Ljotić. On 6 October, Milan Nedić, the Prime Minister of the Axis-installed puppet Government of National Salvation, appointed Mušicki to lead the Serbian Volunteer Command (, SDK). Mušicki was involved in executing Serb civilians in the town of Čačak in December 1941. He and Milan Aćimović contacted Chetnik leader Draža Mihailović on 5 December, possibly in an effort to warn him in advance of the assault the Germans had planned, codenamed Operation Mihailovic. This action prompted the Germans to question Mušicki's loyalty. He was removed from command at the end of 1941 and imprisoned by the Germans, but was later freed at Nedić's intervention.
 Links: a. Royal Yugoslav Army b. Operation Mihailovic c. Dimitrije Ljotić d. Government of National Salvation
Example Output: b

Example 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
Example Output: c

Example Input: Question: Who is the most famous member of the fraternity established at the University of Alabama in 1855? Passage:Greek letter organizations (GLOs) first appeared at the university in 1847 when two men visiting from Yale University installed a chapter of Delta Kappa Epsilon. When DKE members began holding secret meetings in the old state capitol building that year, the administration strongly voiced its disapproval. Over a few more decades, 7 other fraternities appeared at UA: Alpha Delta Phi in 1850, Phi Gamma Delta in 1855, Sigma Alpha Epsilon in 1856 (this was the founding chapter), Kappa Sigma in 1867, Sigma Nu in 1874, Sigma Chi in 1876, and Phi Delta Theta in 1877. Anti-fraternity laws were imposed that year, but were lifted in the 1890s. Women at the university founded the Zeta chapter of Kappa Delta sorority in 1903. Alpha Delta Pi soon followed.
 Links: a. Phi Gamma Delta b. Kappa Delta c. Sigma Nu d. Yale University
Example Output:
a