Why is a transistor classified as a semiconductor? It behaves like a switch in a circuit. It conducts electricity in a circuit. It has controlled impurities to vary its conductivity. It increases the amplitude of an applied signal.

The correct answer is: C!

Explanation:

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A transistor is not 'classified' as a semiconductor. A transistor is MADE from semiconductor materials. Those are materials that have controlled amounts of impurities that allow their conductivity to be controlled. This behavior of their constituent materials is what makes transistors work.