What best describes a semiconductor?

A semiconductor is best described as a material whose conductivity lies between that of a conductor and an insulator. This unique characteristic is crucial because it allows semiconductors to be manipulated for various electronic applications. Unlike conductors, which have high electrical conductivity, and insulators, which have low electrical conductivity, semiconductors can conduct electricity under certain conditions, such as the addition of impurities (doping) or the application of heat or electric fields.

This property makes semiconductors essential in the field of electronics, particularly in the manufacturing of devices like transistors and diodes. Their ability to control and modify conductivity allows for the development of complex circuits that are fundamental to modern technology. Thus, option C accurately captures the essence of semiconductors and their role in electrical engineering and device fabrication.