General exam question G6A07

WhyA bipolar transistor used as a switch operates at the saturation and cutoff points. Used as a switch, a bipolar transistor is driven fully on (saturation, acting like a closed switch with minimal voltage drop) or fully off (cutoff, acting like an open switch with no current flow), answer A. The active region between those two extremes is where a transistor is used for linear amplification, not switching, and "peak and valley" and "enhancement/depletion" describe other devices (tunnel diodes and field-effect transistors) rather than bipolar transistor switching states.