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: In which country is the seaport city of Porto located where the wine received its name "port"? Passage:Port is produced from grapes grown and processed in the demarcated Douro region. The wine produced is then fortified by the addition of a neutral grape spirit known as aguardente to stop the fermentation, leaving residual sugar in the wine, and to boost the alcohol content. The fortification spirit is sometimes referred to as brandy but it bears little resemblance to commercial brandies. The wine is then stored and aged, often in barrels stored in a Lodge (meaning "cellar") as is the case in Vila Nova de Gaia, before being bottled. The wine received its name, "port", in the later half of the 17th century from the seaport city of Porto at the mouth of the Douro River, where much of the product was brought to market or for export to other countries in Europe. The Douro valley where port wine is produced was defined and established as a protected region, and the name Douro thus an official appellation, in 1756, making it the third oldest, after Chianti (1716) and Tokaj (1730).
Links: a. Barrel b. Tokaji c. Vila Nova de Gaia d. Porto
Example Output: d

Example Input: Question: Which team that Lepage drove for after he left Ridling raced in NASCAR first? Passage:Lepage made his Busch Series debut in 1986 at Oxford Plains Speedway, starting 41st and finishing 15th in the No. 09 Buick owned by Carl Merrill. He became a Busch Series regular in 1994, serving as an owner/driver in the No. 71 Vermont Teddy Bear Company car and running for Rookie of the Year honors. He had a best finish of 9th at New Hampshire International Speedway, in which he got a flat tire at the very end of the race, and finished 24th in points. The 1995 season resulted in five Top 10s and finishing 18th in points. At the end of the season, he lost his sponsorship and ran his own car in 1996 unsponsored until April. Lepage then joined David Ridling and his No. 88 Ridling Motorsports team with sponsorship from Ridling's own Farmer's Choice Fertilizer. He won his first career race at the season finale Jiffy Lube Miami 300 with Hype Energy sponsorship. He finished eighth in points with 1 win, three Top 5s and 10 Top 10s. He ran most of the 1997 season driving for Ridling before leaving due to the team losing its sponsor. Lepage would finish out the year running for Phoenix Racing and ST Motorsports. He finished 12th in points, posting three Top 5s and six Top 10s. Lepage had his Cup debut by qualifying for the Fall Charlotte race in the No. 91 LJ Racing car in an impressive 12th. He would also run the Fall Talladega and Atlanta races with finishes of 17th at Talladega and 29th at Atlanta.
Links: a. Oxford Plains Speedway b. Phoenix Racing (NASCAR team) c. Ford EcoBoost 300 d. 1997 NASCAR Busch Series
Example Output: b

Example Input: Question: Did spark gap transmitters have any uses after radio transmitters replaced them? Passage:The discovery of the triode's amplifying ability in 1912 revolutionized electrical technology, creating the new field of electronics, the technology of active (amplifying) electrical devices. The triode was immediately applied to many areas of communication. Triode "continuous wave" radio transmitters replaced the cumbersome inefficient "damped wave" spark gap transmitters, allowing the transmission of sound by amplitude modulation (AM). Amplifying triode radio receivers, which had the power to drive loudspeakers, replaced weak crystal radios, which had to be listened to with earphones, allowing families to listen together. This resulted in the evolution of radio from a commercial message service to the first mass communication medium, with the beginning of radio broadcasting around 1920. Triodes made transcontinental telephone service possible. Vacuum tube triode repeaters, invented at Bell Telephone after its purchase of the Audion rights, allowed telephone calls to travel beyond the unamplified limit of about 800 miles. The opening by Bell of the first transcontinental telephone line was celebrated 3 years later, on January 25, 1915. Other inventions made possible by the triode were television, public address systems, electric phonographs, and talking motion pictures.
Links: a. Amplifier b. Passivity (engineering) c. Damped wave d. Radio broadcasting
Example Output:
c