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 wide is the body of water that separates the Eurasian and North American continents? Passage:The Russian Empire began its interest of the Pacific Northwest in the 18th century, initially curious if there was a land connection between the Eurasian and North American Continents. Two expeditions were led by Vitus Bering, with the findings proving the separation of two continents through the Bering Sea. Being the first European nation to chart much of what comprises the modern American state of Alaska, many locations retain Russian place names. The discovery of sizable fur bearing populations by Bering drew the attention of promyshlenniki previously engaged in the Siberian fur trade. Based out of the Siberian ports of Okhotsk or Petropavlovsk, fur trappers sailed and reported the location of land formations like the Aleutian Islands, Kodiak Island and portions of the Alaskan mainland. Relations with Native Alaskans was often terse due to the uncontrolled actions of particular promyshlenniki who killed and raped Indigenous on islands they trapped furs.
 Links: a. Bering Sea b. Siberia c. Russian Empire d. Bering Sea

Ex Output:
a


Ex 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

Ex Output:
c


Ex Input:
Question: In which of the World War II campaigns that the North Irish Horse participated in did they have the most victories? Passage:The North Irish Horse is a yeomanry unit of the British Territorial Army raised in the northern counties of Ireland in the aftermath of the Second Boer War. Raised and patronized by the nobility from its inception to the present day, it was one of the first non-regular units to be deployed to France and the Low Counties with the British Expeditionary Force in 1914 during World War I and fought with distinction both as mounted troops and later as a Cyclist Regiment, achieving 18 battle honours. The regiment was reduced to a single man in the inter war years and re-raised for World War II, when it achieved its greatest distinctions in the North African and Italian campaigns. Reduced again after the Cold War, the regiment's name still exists in B (North Irish Horse) Squadron, the Scottish and North Irish Yeomanry and 40 (North Irish Horse) Signal Squadron, part of 32 Signal Regiment.
 Links: a. Army Reserve (United Kingdom) b. Army Reserve (United Kingdom) c. Tunisian campaign d. Tunisian campaign

Ex Output:

c