[Q]: Question: "How were the rpms originally determined?"  Context: "In 1925, 78.26 rpm was chosen as the standard because of the introduction of the electrically powered synchronous turntable motor. This motor ran at 3600 rpm, such that a 46:1 gear ratio would produce 78.26 rpm. In parts of the world that used 50 Hz current, the standard was 77.92 rpm (3,000 rpm with a 77:2 ratio), which was also the speed at which a strobe disc with 77 lines would "stand still" in 50 Hz light (92 lines for 60 Hz). After World War II these records were retroactively known as 78s, to distinguish them from other newer disc record formats. Earlier they were just called records, or when there was a need to distinguish them from cylinders, disc records."  Answer:
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[A]: the electrically powered synchronous turntable motor


[Q]: Question: "If an organism is harmed during symbiosis, then that interaction is not considered to be a what?"  Context: "Commensalism describes a relationship between two living organisms where one benefits and the other is not significantly harmed or helped. It is derived from the English word commensal used of human social interaction. The word derives from the medieval Latin word, formed from com- and mensa, meaning "sharing a table"."  Answer:
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[A]: Commensalism


[Q]: Question: "How do affirmative action programs reduce the incentive of upper and middle class blacks to put in effort to succeed?"  Context: "Terry Eastland, the author who wrote From Ending Affirmative Action: The Case for Colorblind Justice states, "Most arguments for affirmative action fall into two categories: remedying past discrimination and promoting diversity". Eastland believes that the founders of affirmative action did not anticipate how the benefits of affirmative action would go to those who did not need it, mostly middle class minorities. Additionally, she argues that affirmative action carries with it a stigma that can create feelings of self-doubt and entitlement in minorities. Eastland believes that affirmative action is a great risk that only sometimes pays off, and that without it we would be able to compete more freely with one another. Libertarian economist Thomas Sowell identified what he says are negative results of affirmative action in his book, Affirmative Action Around the World: An Empirical Study. Sowell writes that affirmative action policies encourage non-preferred groups to designate themselves as members of preferred groups [i.e., primary beneficiaries of affirmative action] to take advantage of group preference policies; that they tend to benefit primarily the most fortunate among the preferred group (e.g., upper and middle class blacks), often to the detriment of the least fortunate among the non-preferred groups (e.g., poor white or Asian); that they reduce the incentives of both the preferred and non-preferred to perform at their best – the former because doing so is unnecessary and the latter because it can prove futile – thereby resulting in net losses for society as a whole; and that they engender animosity toward preferred groups as well.:115–147"  Answer:
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[A]: because doing so is unnecessary


[Q]: Question: "What were the results of the revolt?"  Context: "The Russian Revolution is the series of revolutions in Russia in 1917, which destroyed the Tsarist autocracy and led to the creation of the Soviet Union. Following the abdication of Nicholas II of Russia, the Russian Provisional Government was established. In October 1917, a red faction revolution occurred in which the Red Guard, armed groups of workers and deserting soldiers directed by the Bolshevik Party, seized control of Saint Petersburg (then known as Petrograd) and began an immediate armed takeover of cities and villages throughout the former Russian Empire."  Answer:
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[A]:
The Russian Revolution is the series of revolutions in Russia in 1917, which destroyed the Tsarist autocracy and led to the creation of the Soviet Union