Explanation: An L-network is a fundamental impedance matching circuit consisting of exactly one inductor (L) and one capacitor (C). These components are arranged in a specific "L" shape (either series L, shunt C or series C, shunt L) to transform an input impedance to a desired output impedance. This is crucial in amateur radio to ensure maximum power transfer from a transmitter to an antenna, or between stages of an RF circuit, by matching the source and load impedances. Options A, C, and D are incorrect. A refers to a wireless network, unrelated to the circuit's structure. C describes a characteristic (loss) that any real-world network will have, but it's not the definition of an L-network. D refers to a more complex filter type, not the basic two-element L-network.