Which of the following best describes a transistor?
A) a small electrical circuit made from a semiconductor material such as silicon
B) a cable that transmits bits by means of light pulses along with a glass or plastic fiber instead of electrical signals over a conductor
C) an older information system that remains in use because it still functions and is costly to replace
D) an electronic device that can accept, manipulate, store, and output data, and whose instructions can be programmed