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 long is the fault that lies to the east of Ice Mountain? Passage:Ice Mountain is an arc-shaped forested ridge of the Allegheny Mountains, part of the Ridge-and-valley Appalachians. It is above mean sea level at its summit. Ice Mountain is a large mass of Devonian Oriskany (Ridgeley) sandstone and Marcellus shale with numerous bare rock slopes and vertical cliffs. Ice Mountain lies on the west side of the Timber Mountain anticline and to the west of North Mountain fault, which places it on the Martinsburg allochthonous sheet. Ice Mountain is situated along North River and is known for the several hundred yards of ice that form at its base all year long. At its southern end overlooking the community of North River Mills is located Raven Rocks, a set of stone chimney outcrops. Raven Rocks is in height above mean sea level with vertical cliffs measuring nearly in height. Raven Rocks were named because of the presence of ravens during pioneer days. The present Raven Rocks is the remaining vestige of a once towering cliff that overlooked the North River. Geologically, Ice Mountain is a northern extension of North River Mountain.
Links: a. Anticline b. Fault (geology) c. North Mountain (Virginia-West Virginia) d. Outcrop
Example Output: c

Example Input: Question: How old was Snow Chief in the 1986 Kentucky Derby race? Passage:Solis' first rode in the Kentucky Derby in 1983 on a longshot named Current Hope, and did not place in the money. He rode the Derby again in 1986 on Snow Chief, who had won the Santa Anita Derby and was the morning line favorite, but again finished well back. The horse and rider went on to with the Preakness Stakes that year, marking Solis' only win to date in an American Triple Crown race. He was third in the 1991 Derby on Mane Minister, and also third in the Belmont Stakes on the same horse. Solis finished second in the Kentucky Derby and third in the Preakness with Captain Bodgit in 1997, second in the Derby with Victory Gallop in 1998 and second in both the Derby and the Belmont with Aptitude in 2000. His first Breeders' Cup win was the 2000 Breeders' Cup Sprint on Kona Gold. He won two Breeders' Cup races in 2003 with Johar (who finished in a dead heat) in the Breeders' Cup Turf, and the Breeders' Cup Classic on Pleasantly Perfect, both trained by Richard Mandella. He ended 2003 ranked fourth nationally in purse earnings with a career-best $16,304,252.
Links: a. Breeders' Cup Turf b. Santa Anita Derby c. Snow Chief d. Richard E. Mandella
Example Output: c

Example Input: Question: What country was Metzger born in? Passage:Metzger was born to a Jewish family in Mainz on March 23, 1932, to a hardware store owner and a homemaker. Some of his relatives perished in the Holocaust. At the suggestion of his sisters, Metzger's father moved to the United States in 1937, followed by his wife and sons in January 1938. Henry Metzger attended the Bronx High School of Science, as did his brother, then earned a bachelor's degree from the University of Rochester in 1953, followed by a medical degree at the Columbia University College of Physicians and Surgeons in 1957. Metzger completed his residency at Columbia Presbyterian Hospital, and joined the Public Health Service in 1959, through which he began working at the National Institutes of Health. After two years of post-doctoral study with Seymour Jonathan Singer, funded partly by the Helen Hay Whitney Fellowship, Metzger returned to the National Institutes of Health, working primarily in the National Institute of Arthritis and Musculoskeletal and Skin Diseases.
Links: a. Mainz b. Helen Hay Whitney Foundation c. NewYorkPresbyterian Hospital d. National Institutes of Health
Example Output:
a