Question: Extract the answer to the question from the following context. Question: Which of the following is not the name of a city: Kiev, Byzantium, or Dnieper? Context: Relations between the Rus' and Byzantines became more complex after Oleg took control over Kiev, reflecting commercial, cultural, and military concerns. The wealth and income of the Rus' depended heavily upon trade with Byzantium. Constantine Porphyrogenitus described the annual course of the princes of Kiev, collecting tribute from client tribes, assembling the product into a flotilla of hundreds of boats, conducting them down the Dnieper to the Black Sea, and sailing to the estuary of the Dniester, the Danube delta, and on to Constantinople. On their return trip they would carry silk fabrics, spices, wine, and fruit. The importance of this trade relationship led to military action when disputes arose. The Primary Chronicle reports that the Rus' attacked Constantinople again in 907, probably to secure trade access. The Chronicle glorifies the military prowess and shrewdness of Oleg, an account imbued with legendary detail. Byzantine sources do not mention the attack, but a pair of treaties in 907 and 911 set forth a trade agreement with the Rus', the terms suggesting pressure on the Byzantines, who granted the Rus' quarters and supplies for their merchants and tax-free trading privileges in Constantinople.
Answer: Dnieper

Question: Extract the answer to the question from the following context. Question: whato was a manufacturer of electric motors? Context: During 1889, Thomas Edison had business interests in many electricity-related companies: Edison Lamp Company, a lamp manufacturer in East Newark, New Jersey; Edison Machine Works, a manufacturer of dynamos and large electric motors in Schenectady, New York; Bergmann & Company, a manufacturer of electric lighting fixtures, sockets, and other electric lighting devices; and Edison Electric Light Company, the patent-holding company and the financial arm backed by J.P. Morgan and the Vanderbilt family for Edison's lighting experiments. In 1889, Drexel, Morgan & Co., a company founded by J.P. Morgan and Anthony J. Drexel, financed Edison's research and helped merge those companies under one corporation to form Edison General Electric Company which was incorporated in New York on April 24, 1889. The new company also acquired Sprague Electric Railway & Motor Company in the same year.
Answer: Edison Machine Works

Question: Extract the answer to the question from the following context. Question: How is it found on Earth? Context: Copper is synthesized in massive stars and is present in the Earth's crust at a concentration of about 50 parts per million (ppm), where it occurs as native copper or in minerals such as the copper sulfides chalcopyrite and chalcocite, the copper carbonates azurite and malachite, and the copper(I) oxide mineral cuprite. The largest mass of elemental copper discovered weighed 420 tonnes and was found in 1857 on the Keweenaw Peninsula in Michigan, US. Native copper is a polycrystal, with the largest described single crystal measuring 4.4×3.2×3.2 cm.
Answer:
native copper or in minerals