instruction:
This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.
question:
Passage: Naturally occurring glass, especially the volcanic glass obsidian, has been used by many Stone Age societies across the globe for the production of sharp cutting tools and, due to its limited source areas, was extensively traded. But in general, archaeological evidence suggests that the first true glass was made in coastal north Syria, Mesopotamia or ancient Egypt. The earliest known glass objects, of the mid third millennium BCE, were beads, perhaps initially created as accidental by-products of metal-working (slags) or during the production of faience, a pre-glass vitreous material made by a process similar to glazing. Question: What was obsidian used to make in prehistoric times?
answer:
cutting tools

question:
Passage: While most of mainland Greece and the Aegean islands was under Ottoman control by the end of the 15th century, Cyprus and Crete remained Venetian territory and did not fall to the Ottomans until 1571 and 1670 respectively. The only part of the Greek-speaking world that escaped long-term Ottoman rule was the Ionian Islands, which remained Venetian until their capture by the First French Republic in 1797, then passed to the United Kingdom in 1809 until their unification with Greece in 1864.[page needed] Question: The Ottomans controlled what islands b y the end of the 15th century?
answer:
Aegean islands

question:
Passage: On June 12, 1990, the Congress of People's Deputies of the Republic adopted the Declaration of State Sovereignty of the Russian SFSR, which was the beginning of the "War of Laws", pitting the Soviet Union against the Russian Federation and other constituent republics. Question: What government was the Russian Federation fighting against during this period?
answer:
the Soviet Union