The following statements all refer to the human brain when mental activity is occurring. Which statement is correct?
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In order to detect electric currents in the brain, you must open the skull and make direct electrical contact with the brain.
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The electric currents in the brain can be detected outside the brain by detecting the magnetic fields they produce.
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The electric currents in the brain can be mapped by shaving a person's head and dropping iron filings on the head.
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The electric currents in the brain produce an aura that can be detected visually.
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The electric currents in the brain cannot be detected by any means.