Which term refers to a frequency that can be modulated to carry intelligible information?

The term "carrier frequency" refers to a specific frequency that is modulated in order to transmit information effectively. In communications, a carrier frequency acts as a baseline signal that can be varied in amplitude, frequency, or phase to encode information, such as voice or data. This modulation process allows the carrier frequency to carry intelligible information over long distances, making it crucial in various forms of communication systems, including radio and television broadcasting, as well as in wireless communications.

While a modulating signal is involved in changing the carrier frequency, it does not itself serve as the frequency that carries information. Instead, the modulating signal provides the changes that are applied to the carrier frequency to encode the message. The term “intelligence” in this context typically refers to the information being transmitted, rather than the frequency itself. Detection involves receiving and interpreting the modulated signal but does not pertain directly to the definition of a frequency used for carrying information. Therefore, "carrier frequency" is the most appropriate term in this context.