CXD逻辑34,N哥请进!

Playing eighteenth-century music on the instruments of that period provides valuable information about how the music originally sounded. Eighteenth-century instruments cannot be played without being restored,however,and restoring such an instrument destroys all of the information that researchers could obtain from itabout eighteenth-century instrument-making techniques.
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 een restored
e) An eighteenth-century instrument cannot serve as a source of new information about eighteenth-century in strument-making techniques once it can be played
c,e选不下来