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 old was Nusslein-Volhard when she won the Nobel Prize in Physiology and Medicine? Passage:The concept of the morphogen has a long history in developmental biology, dating back to the work of the pioneering Drosophila (fruit fly) geneticist, Thomas Hunt Morgan, in the early 20th century. Lewis Wolpert refined the morphogen concept in the 1960s with the French flag model, which described how a morphogen could subdivide a tissue into domains of different target gene expression (corresponding to the colours of the French flag). This model was championed by the leading Drosophila biologist, Peter Lawrence. Christiane Nusslein-Volhard was the first to identify a morphogen, Bicoid, one of the transcription factors present in a gradient in the Drosophila syncitial embryo. She was awarded the 1995 Nobel Prize in Physiology and Medicine for her work explaining the morphogenic embryology of the common fruit fly. Groups led by Gary Struhl and Stephen Cohen then demonstrated that a secreted signalling protein, Decapentaplegic (the Drosophila homologue of transforming growth factor beta), acted as a morphogen during the later stages of Drosophila development.
 Links: a. Christiane Nüsslein-Volhard b. Lewis Wolpert c. Lewis Wolpert d. Transcription factor

Ex Output:
a


Ex Input:
Question: Were there any famous performers at the music festival McCollum often performed at? Passage:During the mid-1950s McCollum was highly busy performing as a concert soloist and performed with some frequency in operas with the New England Opera Theatre (NEOT). He sang frequently with the Boston Symphony Orchestra under conductor Charles Munch, often at the Tanglewood Music Festival, performing works like the role of the evangelist in Bach's Johannes Passion (1956). He was also a regular performer with the Dessoff Choirs under conductor Paul Boepple, performing as a tenor soloist in oratorios like Handel's Messiah (1956) and Handel's Israel in Egypt (1957). One work which he performed with frequency during these years was J.S. Bach's Mass in B Minor, which he first performed in February 1955 with the Chicago Symphony Orchestra under conductor Margaret Hillis. He later performed the work with the Boston Symphony Orchestra at Tanglewood in the summer of 1955 and with the Philadelphia Orchestra at the Bethlehem Bach Festival in 1956. In March 1955 he sang Helenus in a lauded production of Berlioz's Les Troyens with the New England Opera Theater opposite Eunice Alberts as Cassandre, Marriquita Moll as Dido, and Arthur Schoep as Aeneas.
 Links: a. Tanglewood Music Festival b. George Frideric Handel c. Johann Sebastian Bach d. Mass in B minor

Ex Output:
a


Ex Input:
Question: How long did the Korean War last? Passage:The Battle of Pakchon (5 November 1950), also known as the Battle of Bochuan (), took place ten days after the start of the Chinese First Phase Offensive, following the entry of the Chinese People's Volunteer Army (PVA) into the Korean War. The offensive reversed the United Nations Command (UN) advance towards the Yalu River which had occurred after their intervention in the wake of the North Korean invasion of South Korea at the start of the war. The battle was fought between British and Australian forces from the 27th British Commonwealth Brigade with American armour and artillery in support, and the PVA 117th Division of the 39th Army, around the village of Pakchon on the Taeryong River. After capturing Chongju on 30 October the British and Australians had been ordered to pull back to Pakchon in an attempt to consolidate the western flank of the US Eighth Army. Meanwhile, immediately following their success at Unsan against the Americans, the PVA 117th Division had attacked southward, intending to cut off the UN forces as they withdrew in the face of the unexpected PVA assault. To halt the PVA advance, the 27th British Commonwealth Brigade was ordered to defend the lower crossings of the Taeryong and Chongchon rivers as part of a rearguard, in conjunction with the US 24th Infantry Division further upstream on the right.
 Links: a. 24th Infantry Division (United States) b. Korean War c. Korean War d. South Korea

Ex Output:

b