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.

[Q]: Passage: The preludes, many of which are very brief (some consisting of simple statements and developments of a single theme or figure), were described by Schumann as "the beginnings of studies". Inspired by J.S. Bach's The Well-Tempered Clavier, Chopin's preludes move up the circle of fifths (rather than Bach's chromatic scale sequence) to create a prelude in each major and minor tonality. The preludes were perhaps not intended to be played as a group, and may even have been used by him and later pianists as generic preludes to others of his pieces, or even to music by other composers, as Kenneth Hamilton suggests: he has noted a recording by Ferruccio Busoni of 1922, in which the Prelude Op. 28 No. 7 is followed by the Étude Op. 10 No. 5. Question: What piece of Bach's did Chopin take inspiration for his preludes?
[A]: The Well-Tempered Clavier


[Q]: 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?
[A]: cutting tools


[Q]: Passage: After Germany invaded the Soviet Union on 22 June 1941, the Wehrmacht crossed the Estonian southern border on 7 July. The Red Army retreated behind the Pärnu River – Emajõgi line on 12 July. At the end of July the Germans resumed their advance in Estonia working in tandem with the Estonian Forest Brothers. Both German troops and Estonian partisans took Narva on 17 August and the Estonian capital Tallinn on 28 August. After the Soviets were driven out from Estonia, German troops disarmed all the partisan groups. Question: When did the Werhmacht cross south border of Estonia?
[A]:
7 July