Brain-scanning technology provides information about processes occurring in the brain. For this information to help researchers understand how the brain enables us to think, however, researchers must be able to rely on the accuracy of the verbal reports given by subjects while their brains are being scanned. Otherwise brain-scan data gathered at a given moment might not contain information about what the subject reports thinking about at that moment, but instead about some different set of thoughts. Which one of the following most accurately expresses the main conclusion of the argument? ['It is unlikely that brain-scanning technology will ever enable researchers to understand how the brain enables us to think.', 'Information from brain scans can help researchers understand how the brain enables us to think only if the verbal reports of those whose brains are being scanned are accurate.', 'Because subjects whose brains are being scanned may not accurately report what they are thinking, the results of brain-scanning research should be regarded with great skepticism.', 'There is no way that researchers can know for certain that subjects whose brains are being scanned are accurately reporting what they are thinking.']