Explanation: A DAC, or Digital-to-Analog Converter, is an integrated circuit that performs the essential function of transforming digital data (typically binary numbers) into a corresponding analog electrical signal, such as a voltage or current. In amateur radio, DACs are crucial for various applications, including synthesizing RF waveforms, generating modulated signals, producing audio output from digital signal processing (DSP), and controlling analog parameters with digital inputs. Conversely, an ADC (Analog-to-Digital Converter) performs the opposite function, converting analog signals into digital data. This is vital for digitizing received signals for DSP or for inputting sensor data into a microcontroller. Options B (DCC) and C (CDC) do not refer to standard integrated circuits used for signal conversion in electronics. DCC often refers to Digital Command Control in model railroading, and CDC is a generic acronym with various meanings not related to signal conversion.