GRE Reading Comprehension

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Source: NO4

It is a popular misconception that nuclear fusion power is free of radioactivity; in fact, the deuterium-tritium reaction that nuclear scientists are currently exploring with such zeal produces both alpha particles and neutrons, (The neutrons are used to produce tritium from a lithium blanket surrounding the reactor.) Another common misconception is that nuclear fusion power is a virtually unlimited source of energy because of the enormous quantity of deuterium in the sea. Actually, its limits are set by the amount of available lithium, which is about as plentiful as uranium in the Earth's crust. Research should certainly continue on controlled nuclear fusion,but 　　no energy program should be premised on its existence until it has proven practical. For the immediate future, we must continue to use hydroelectric power, nuclear fission, and fossil fuels to meet our energy needs. The energy sources already in major use are in major use for good reason.

Question List: 1 2 3 4

The primary purpose of the passage is to

  • A criticize scientists who believe that the deuterium-tritium fusion reaction can be made feasible as an energy source
  • B admonish scientists who have failed to correctly calculate the amount of lithium
  • C defend the continued short-term use of fossil fuels as a major energy source
  • D caution against uncritical embrace of nuclear fusion power as a major energy source
  • E correct the misconception that nuclear fusion power is entirely free of radioactivity

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