Explanation: A CODEC (COder/DECoder) is specialized circuitry or an integrated circuit designed to convert analog signals, such as human voice, into a digital format. This digital stream can then be processed, compressed, encrypted, and transmitted more efficiently. Conversely, it also performs the reverse function: decoding a received digital signal back into its original analog form for output, like through a speaker. This process is fundamental to modern digital voice modes used in amateur radio, such as D-STAR, DMR, and Fusion, which rely on converting microphone audio into digital data packets and back again. Options A, B, and D are incorrect. A CODEC's primary role isn't just Morse code decoding, nor is its acronym "computer operated digital encoding compandor." While it may involve compression, its core function is the complete analog-to-digital and digital-to-analog conversion.