GMAT Critical Reasoning (CR) | Solar energy plants use a number of mirrors to focus sunligh

Solar energy plants use a number of mirrors to focus sunlight and produce electricity for about ten cents per kilowatt hour. The problem with the wide spread acceptance of solar energy plants is that electricity can be generated from coal for seven cents per kilowatt hour. In a free market system consumers will choose the lowest-cost form of electricity. Consequently, there will not be a market for the electricity produced by solar energy plants.

Which of the following, if true, does most to weaken
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