If the statements above are true, which of the following must be true on the basis of them? A. Eighteenth-century instruments cannot be used to provide information about the original techniques used in playing such instruments if they have been restored. B. Eighteenth-century instruments that have been restored can provide information only about how eighteenth-century music originally sounded C. Eighteenth-century instruments are the only source of information about the instrument-making techniques of that period. D. An eighteenth-century instrument that has not been restored can provide more information than can one that has been restored. E. An eighteenth-century instrument cannot serve as a source of new information about eighteenth-century instrument-making techniques once it can be played