[Q]: Extract the answer to the question from the following context. Question: How is the bouncing of rays used? Context: A CD is read by focusing a 780 nm wavelength (near infrared) semiconductor laser housed within the CD player, through the bottom of the polycarbonate layer. The change in height between pits and lands results in a difference in the way the light is reflected. By measuring the intensity change with a photodiode, the data can be read from the disc. In order to accommodate the spiral pattern of data, the semiconductor laser is placed on a swing arm within the disc tray of any CD player. This swing arm allows the laser to read information from the centre to the edge of a disc, without having to interrupt the spinning of the disc itself.
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[A]: The change in height between pits and lands results in a difference in the way the light is reflected


[Q]: Extract the answer to the question from the following context. Question: What is the name of a U.S. hit that came before the hit that had radio airplay in clubs referred as ghetto house subgenre? Context: Influential gospel/R&B-influenced Aly-us released "Time Passes On" in 1993 (Strictly Rhythm), then later, "Follow Me" which received radio airplay as well as being played in clubs. Another U.S. hit which received radio play was the single "Time for the Perculator" by Cajmere, which became the prototype of ghetto house subgenre. Cajmere started the Cajual and Relief labels (amongst others). By the early 1990s artists such as Cajmere himself (under that name as well as Green Velvet and as producer for Dajae), DJ Sneak, Glenn Underground and others did many recordings. The 1990s saw new Chicago house artists emerge such as DJ Funk, who operates a Chicago house record label called Dance Mania. Ghetto house and acid house were other house music styles that were also started in Chicago.
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[A]: Aly-us released "Time Passes On"


[Q]: Extract the answer to the question from the following context. Question: What other attributes were included with his idea of equality later on? Context: On September 21, 1953, Thomas Watson, Jr., the company's president at the time, sent out a controversial letter to all IBM employees stating that IBM needed to hire the best people, regardless of their race, ethnic origin, or gender. He also publicized the policy so that in his negotiations to build new manufacturing plants with the governors of two states in the U.S. South, he could be clear that IBM would not build "separate-but-equal" workplaces. In 1984, IBM added sexual orientation to its nondiscrimination policy. The company stated that this would give IBM a competitive advantage because IBM would then be able to hire talented people its competitors would turn down.
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[A]: IBM added sexual orientation to its nondiscrimination policy


[Q]: Extract the answer to the question from the following context. Question: How could the problem of "where" have been answered easily? Context: Early releases of the Washington coin included error coins shipped primarily from the Philadelphia mint to Florida and Tennessee banks. Highly sought after by collectors, and trading for as much as $850 each within a week of discovery, the error coins were identified by the absence of the edge impressions "E PLURIBUS UNUM IN GOD WE TRUST 2007 P". The mint of origin is generally accepted to be mostly Philadelphia, although identifying the source mint is impossible without opening a mint pack also containing marked units. Edge lettering is minted in both orientations with respect to "heads", some amateur collectors were initially duped into buying "upside down lettering error" coins. Some cynics also erroneously point out that the Federal Reserve makes more profit from dollar bills than dollar coins because they wear out in a few years, whereas coins are more permanent. The fallacy of this argument arises because new notes printed to replace worn out notes, which have been withdrawn from circulation, bring in no net revenue to the government to offset the costs of printing new notes and destroying the old ones. As most vending machines are incapable of making change in banknotes, they commonly accept only $1 bills, though a few will give change in dollar coins.
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[A]:
opening a mint pack also containing marked units