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: When was the man whose name is used as the unit of radio wave frequency born?  Passage:A modulated radio wave, carrying an information signal, occupies a range of frequencies. See diagram. The information (modulation) in a radio signal is usually concentrated in narrow frequency bands called sidebands (SB) just above and below the carrier frequency. The width in hertz of the frequency range that the radio signal occupies, the highest frequency minus the lowest frequency, is called its bandwidth (BW). A given amount of bandwidth can carry the same amount of information (data rate in bits per second) regardless of where in the radio frequency spectrum it is located, so bandwidth is a measure of information-carrying capacity. The bandwidth required by a radio transmission depends on the data rate of the information (modulation signal) being sent, and the spectral efficiency of the modulation method used; how much data it can transmit in each kilohertz of bandwidth. Different types of information signals carried by radio have different data rates. For example, a television (video) signal has a greater data rate than an audio signal.
 Links: a. Data signaling rate b. Carrier wave c. Hertz d. Audio signal

Ex Output:
c


Ex Input:
Question: On what day was the inauguration of the president who held a ceremony on the banks of the scenic New River to designate it as an American Heritage River? Passage:Ashe County has been home to, produced, or been visited by, several prominent people. It is the hometown of Monte Weaver from Helton who pitched for the Washington Senators and pitched a World Series game in 1933. After being traded from the Senators, he pitched for the Boston Red Sox, before being called into service in World War II. Weaver died in 1994. Albert Hash a well-known and beloved fiddler and instrument maker at one time resided in Lansing. Helen Keller visited an Ashe County native, Marvin Osborne, in 1944 when he was wounded in France in World War II. Loretta Lynn sang at the Central Food Market in West Jefferson in the late 1960s (the Central Food building formally housed a locally owned auto parts store and is now the location of a local restaurant). Roni Stoneman was a visitor to Ashe Park in the 1980s. In 1998, then-President Bill Clinton and his Vice-President, Al Gore, held a ceremony on the banks of the scenic New River to designate it as an American Heritage River. After the ceremony, both men had lunch at the historic Glendale Springs Inn, also located in Ashe County. Fiddle player G. B. Grayson was born in Ashe County in 1887.
 Links: a. Loretta Lynn b. Al Gore c. History of the Washington Senators (1901–1960) d. Bill Clinton

Ex Output:
d


Ex Input:
Question: When was the birthplace of Ptacek founded? Passage:Ptacek was born in East Berlin to a family of Czech and German descent. His family fled East Germany for the United States when he was five years old. They eventually settled in Chicago, where young Ptacek was first exposed to blues music. He moved to Tucson in the early 1970s, where he began his own musical career, most often solo, but sometimes he plugged in and led a trio as Rainer & Das Combo. He co-founded Giant Sandworms with Howe Gelb in the late 1970s. When the band decided to move to New York and became Giant Sand, Ptacek opted to stay in Tucson to make sure that he would not disrupt his then-new family. Although he never became well known in the United States, he became more and more recognized in Europe. ZZ Top guitarist Billy Gibbons was so impressed with the singer-guitarist that he arranged to have Kurt Loder review Ptacek's "Mush Mind Blues" cassette in Rolling Stone. Ptacek later traveled to Houston at the invitation of Billy Gibbons to record at Gibbons' Gold Star Sound Services studio which saw release as "The Texas Tapes" meeting international attention and approval. Robert Plant, similarly impressed, flew Ptacek to England for the sessions for B-sides to supplement the singles from Fate of Nations.
 Links: a. East Berlin b. Howe Gelb c. Giant Sand d. United States

Ex Output:

a