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: Was the head of the Swedish Institute for Race Biology still alive hen Gunther was professor at Albert Ludwigs University? Passage:In 1919, after the end of the war, he started his writing career. He wrote a polemical work entitled "The Knight, death and the devil: the heroic idea", a reworking of the tradition of German Pagan-Nationalist Romanticism into a form of "biological nationalism". Heinrich Himmler was very impressed by this book. In 1922 Gunther studied at the University of Vienna while working in a museum in Dresden. In 1923 he moved to Scandinavia to live with his second wife, who was Norwegian. He received scientific awards from the University of Uppsala and the Swedish Institute for Race Biology, headed by Herman Lundborg. In Norway he met Vidkun Quisling. In May 1930 he was appointed to the University of Jena by Wilhelm Frick who had become the first NSDAP minister in a state government when he was appointed minister of education in the right-wing coalition government formed in Thuringen following an election in December 1929. In 1935 he became a professor at the University of Berlin, teaching race science, human biology and rural ethnography. From 1940 to 1945 he was professor at Albert Ludwigs University.
Links: a. Nazi Party b. Herman Bernhard Lundborg c. Scandinavia d. Vidkun Quisling
Example Output: b

Example 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 Nusslein-Volhard b. Lewis Wolpert c. Lewis Wolpert d. Transcription factor
Example Output: a

Example Input: Question: Who is the current mayor of the city located on the northern Great Plains that the Yellowstone River flow through? Passage:The river rises in northwestern Wyoming in the Absaroka Range, on the Continental Divide in southwestern Park County. The river starts where the North Fork and the South Fork of the Yellowstone River converge. The North Fork, the larger of the two forks, flows from Younts Peak. The South Fork flows from the southern slopes of Thorofare Mountain. The Yellowstone River flows northward through Yellowstone National Park, feeding and draining Yellowstone Lake, then dropping over the Upper and Lower Yellowstone Falls at the head of the Grand Canyon of the Yellowstone within the confines of the park. After passing through the Black Canyon of the Yellowstone downstream of the Grand Canyon, the river flows northward into Montana between the northern Absaroka Range and the Gallatin Range in Paradise Valley. The river emerges from the mountains near the town of Livingston, where it turns eastward and northeastward, flowing across the northern Great Plains past the city of Billings.
Links: a. Gallatin Range b. Billings, Montana c. Yellowstone Falls d. Billings, Montana
Example Output:
b