Explanation: Bipolar Junction Transistors (BJTs) are fundamental active semiconductor devices used extensively in amateur radio circuits for amplification, switching, and oscillation. The three terminals of a BJT are the **Base**, **Collector**, and **Emitter**. The Base acts as the control terminal, regulating the current flow between the Collector and Emitter, thereby enabling amplification. The Emitter "emits" charge carriers, and the Collector "collects" them. Option A, Cathode, plate, and grid, refers to the terminals of a vacuum tube. Option C, Gate, source, and drain, refers to the terminals of a Field-Effect Transistor (FET), another type of transistor, but distinct from a bipolar transistor. Option D, Input, output, and ground, are functional descriptions of how a device might be used in a circuit, not the names of its physical terminals.