In this task, you're given a passage, further information available on a particular linked term from the statement, and a question. Your job is to generate the answer to the question by using the information provided. If there is no clear answer obtainable, output 'none'.

Passage: Indigenous peoples inhabited Missouri for thousands of years before European exploration and settlement. Archaeological excavations along the rivers have shown continuous habitation for more than 7,000 years. Beginning before 1000 CE, there arose the complex Mississippian culture, whose people created regional political centers at present-day St. Louis and across the Mississippi River at Cahokia, near present-day Collinsville, Illinois. Their large cities included thousands of individual residences, but they are known for their surviving massive earthwork mounds, built for religious, political and social reasons, in platform, ridgetop and conical shapes. Cahokia was the center of a regional trading network that reached from the Great Lakes to the Gulf of Mexico. The civilization declined by 1400 CE, and most descendants left the area long before the arrival of Europeans. St. Louis was at one time known as Mound City by the European Americans, because of the numerous surviving prehistoric mounds, since lost to urban development. The Mississippian culture left mounds throughout the middle Mississippi and Ohio river valleys, extending into the southeast as well as the upper river.
Link Information: earthworks are artificial changes in land level, typically made from piles of artificially placed or sculpted rocks and soil. Question: What are earthwork mounds made of?
Answer: sculpted rocks and soil.

Passage: A large portion of the Vilnius area was controlled by the Second Polish Republic during the interwar period, particularly the area of the Republic of Central Lithuania, which had a significant Polish speaking population. For example, the Wilno Voivodeship (25% of it is a part of modern Lithuania and 75% - modern Belarus) in 1931 contained 59.7% Polish speakers and only 5.2% Lithuanian speakers; see Ethnic history of the region of Vilnius for details. From 1918 to 1921 there were several conflicts, such as the activity of the Polish Military Organization, Sejny uprising (that was met with massive outrage in Lithuania) and a discovered attempt at a Polish coup on the Lithuanian government. From the documents stolen from Polish Military Organization headquarters safe in Vilnius and given to Prime Minister of Lithuania Augustinas Voldemaras, it is clear that this plot was directed by Jozef Pisudski himself. The Polish-Lithuanian War and Zeligowski's Mutiny contributed to a worsening of Polish-Lithuanian relations; increasingly Polish people were viewed with suspicion in Lithuania. The loss of Vilnius was a stunning blow to Lithuanian aspirations and identity, and the unrelenting irredentist demand for its return became one of the most important elements of Lithuanian political and social life in the interwar period. The irredentist campaign resulted in the emergence of feelings of hatred and revenge directed against the Poles in the Lithuanian society. In fact, the largest social organization in interwar Lithuania was the League for the Liberation of Vilnius, which propagated irredentist views in its magazine Musu Vilnius (Our Vilnius).
Link Information: refers to a Polish uprising against the Lithuanian authorities in August 1919 Question: Which of the conflicts that occured between 1918 and 1921 occured first?
Answer: activity of the Polish Military Organization

Passage: Graham Clarke was born in Holy Name Medical Center in Teaneck, New Jersey on July 11, 1970. Clarke's parents, Lorain Maria Clarke (nee Meola), a homemaker, and Thomas Michael "Moose" Clarke, a stockbroker were married in 1960 and had three children before Graham: Thomas in 1961, Dennis in 1962, and Martin in 1965. He spent the first seven years of his life in a split-level home in Dumont, New Jersey. He was frequently in the room when his older brother Tommy would have guitar lessons with musician Bob Berger. Bob noted one time when a screaming Graham had scarlet fever "That boy's screaming on key! That's a C note." Such exposure to music had an obvious influence on him and there is an oft-told family story that claims the first song Graham ever learned to sing was "Me and Julio Down by the Schoolyard," a popular song Tommy was learning on the guitar at the time. At the age of seven, his family moved one town over to Oradell, where he attended St. Joseph Grammar School, and later Bergen Catholic High School. Neither school had a music program so Graham taught himself how to play the guitar using his brother's old fake books.
Link Information: "Me and Julio Down by the Schoolyard" is a song by American singer-songwriter Paul Simon Question: Who wrote the first song that Graham Clark learned to sing?
Answer: Paul Simon