What is the process called that involves mixing two radio signals, such as a carrier wave and a data signal?

The correct answer is modulation. Modulation is the process by which a carrier wave is varied in order to encode information from a data signal. In this process, the characteristics of the carrier wave—such as its amplitude, frequency, or phase—are modified in accordance with the data being transmitted. This mixing allows the data signal to be effectively superimposed on the carrier wave, enabling long-range transmission of the information over various mediums, including air.

Understanding modulation is essential for telecommunications as it enables the efficient transfer of data over distances, making it a fundamental technique in both analog and digital communication systems.