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 what modern day countries did the band of nomads who visited the Hami Desert live? Passage:Beyond an occasional visit from a band of nomad Mongols, this region of the Pe-shan swelling is entirely uninhabited. And yet it was from this region, according to Grigory Grum-Grshimailo (1889-1890 explorer), that the Yue-chi (Yuezhi), a nomadic people akin to the Tibetans, proceeded when, towards the middle of the 2nd century BC, they moved westwards and settled near Lake Issyk-kul; and from here proceeded also the Shanshani, or people who some two thousand years ago founded the state of Shanshan or Lofi-lan. The ruins of this town were discovered by Sven Hedin in the desert of Lop in 1901. Here, says the Russian explorer, the Huns gathered strength, as also did the Turks (Ch. Tukiu) in the 6th century, and the Uighur tribes and the rulers of the Tangut kingdom. But after Genghis Khan, in the 12th century, drew away the peoples of this region, and no others came to take their place, the country went out of cultivation and eventually became the barren desert it is now. During the Hun time, and probably into the Middle Ages, the present desert was a lush steppe grassland able to support sustainable seasonal nomadic horse husbandry on a large scale.
Links: a. Shanshan b. Shanshan c. Mongols d. Issyk-Kul
Example Output: c

Example Input: Question: How many square miles is the town where the route from West Virginia split? Passage:By 1947, present Interstate 70 across Pennsylvania was included in the planned Interstate Highway System. The route from West Virginia split at Washington, with one branch heading northeast to meet the Pennsylvania Turnpike near Pittsburgh and the other heading east, bypassing Pittsburgh to the south (via a planned bypass of Pennsylvania Route 71) to the New Stanton interchange. The piece south from the Breezewood interchange into Maryland was also in the network. The route between US 30 in Breezewood and US 522 in Warfordsburg was originally known as Pennsylvania Route 126. In 1957, preliminary numbers were assigned; the longer route via Pittsburgh (now Interstate 79 and Interstate 376) became the main line of I-70, while the southern bypass (now I-70) became Interstate 70S. The section of present-day I-70 between PA 519 near Washington and New Stanton was built as a four-lane divided highway known as the "Express Highway"; this road was assigned the temporary PA 71 Alternate designation in 1957 and would be designated as I-70S following the completion of additional connecting roads in the Interstate Highway System. On July 15, 1960, I-70 was designated onto the Penn-Lincoln Parkway. A southern extension of Interstate 79 (which had previously only run from Erie south to Pittsburgh) to Charleston, West Virginia in 1963 resulted in changes to I-70. On February 26, 1964, as part of the formation of Interstate 76 (east of downtown Pittsburgh), AASHTO approved a rerouting of I-70 along I-70S. The former I-70 became I-79 from Washington to downtown Pittsburgh and I-76 to and along the Turnpike to New Stanton. This brought the routing of I-70 to its present form.
Links: a. Charleston, West Virginia b. Washington, Pennsylvania c. Pittsburgh d. Interstate 79
Example Output: b

Example Input: Question: What is the population of the city where Lack was born? Passage:Fredell Lack was born in Tulsa, Oklahoma, the oldest of three children of Jewish Eastern European (Latvian) immigrants, Abram I. Lack and Sarah Stillman Lack (who was a sister of noted painter Ary Stillman). She began violin lessons at age six, studying with Tosca Berger. When Fredell was 10, she moved with her family to Houston, Texas. There she studied with Josephine Boudreaux, the concertmaster of the Houston Symphony. At age 11, she first soloed with orchestra, performing the Wieniawski Concerto No. 2 with the Tulsa Philharmonic. At 12, Lack was accepted into the New York City studio of the legendary violinist and pedagogue Louis Persinger, whose other students included such artists as Yehudi Menuhin, Isaac Stern, and Ruggiero Ricci. She moved to New York and completed her pre-college schooling at the Bentley School while continuing her violin lessons with Persinger. At 17, she made her professional solo debut, playing the Mendelssohn Violin Concerto with the St. Louis Symphony. Subsequently she received a full scholarship to the Juilliard School in New York. She continued studying violin with Persinger there and also was deeply influenced by her study of chamber music with Felix Salmond. She received the Diploma from Juilliard at age 21.
Links: a. Tulsa, Oklahoma b. Ary Stillman c. Felix Salmond d. Violin Concerto No. 2 (Wieniawski)
Example Output:
a