Explanation: A Software Defined Radio (SDR) represents a fundamental shift in radio architecture. Traditionally, many radio functions like tuning, filtering, modulation, and demodulation were performed by dedicated analog hardware components (e.g., crystals, resistors, capacitors). An SDR moves a significant portion of these signal processing tasks from fixed hardware into software running on a computer or specialized digital processor. The radio signal is digitized at an early stage in the receive chain (or converted from digital to analog late in the transmit chain), and then all subsequent processing is performed digitally by software. This approach offers tremendous flexibility; the radio's characteristics and capabilities can be changed or upgraded simply by modifying the software, enabling new operating modes, features, and powerful visualization tools like waterfall displays without requiring hardware alterations. Options A, C, and D are incorrect: "Software Deviation Ratio" is not a recognized radio term. An "SWR Meter" is a device used to measure the Standing Wave Ratio of an antenna system, unrelated to radio processing. "Static Dynamic Ram" refers to types of computer memory, which are entirely separate from radio functionality.