Which of the following terms best describes the process of controlling the properties of a carrier signal so that the signal contains the information to be transmitted?

The process of controlling the properties of a carrier signal to embed information for transmission is known as modulation. This involves varying certain characteristics of the carrier wave, such as its amplitude, frequency, or phase, according to the information being sent. The primary goal of modulation is to enable the efficient transmission of signals over various media, enhancing the signal's ability to carry the necessary information over long distances.

For example, in analog modulation, techniques like amplitude modulation (AM) and frequency modulation (FM) adjust the amplitude or frequency of the carrier wave to correspond with the variations in the input signal. In digital modulation, methods such as phase-shift keying or quadrature amplitude modulation alter the carrier in discrete steps based on the digital data being transmitted.

Each of the other choices represents different aspects of signal processing. Demodulation refers to extracting the original information from a modulated carrier signal, essentially the reverse of modulation. Encoding involves converting data into a specific format or code for efficient transmission or storage, and transmission pertains to the process of sending the modulated signal over a channel or medium but does not alone imply the modification of the carrier signal. Therefore, modulation is the most accurate term for the described process of preparing a carrier signal with information.