Which of the following would not be a cause of a real business cycle?

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a. a decrease in government borrowing

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b. a drought in the Midwest

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c. oil prices skyrocketing as a result of an accident on the world’s largest offshore oil rig

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d. a labor strike that cripples the steel industry

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e. an improvement in the technology for solar energy that yields a lightweight solar battery that can be used to power cars for long trips