Which object does not depend on changing one form of energy to a different form?
D None of these
C IS NOT STETHOSCOPE IT IS A CD WITH A CABLE . A CD HAS CHEMICAL ENERGY [BATTERY] AND IT DOESN'T CONVERT IT INTO ANY OTHER FORM HENCE C IS ALSO CORRECT
A is not correct as it converts wind energy into electrical energy B is not correct as it converts electrical energy int heat energy. and I am not sure what is the c one