The correct answer is A. Amplitude modulated.
Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting information via radio waves. In amplitude modulation, the amplitude (or strength) of a carrier wave is varied in accordance with the instantaneous value of the information signal.
The audio signals of TV are amplitude modulated because this is the most efficient way to transmit them over long distances. AM signals are relatively simple to generate and can be received with relatively simple equipment.
Frequency modulation (FM) is another modulation technique that is sometimes used for transmitting audio signals. In FM, the frequency of the carrier wave is varied in accordance with the instantaneous value of the information signal. FM signals are less susceptible to noise than AM signals, but they are also more complex to generate and receive.
Unmodulated signals are signals that do not have any information encoded on them. They are simply a carrier wave with no changes in its amplitude, frequency, or phase.
Velocity modulation (VM) is a modulation technique that is used to transmit information by varying the velocity of a carrier wave. VM signals are not commonly used in practice, but they have some advantages over other modulation techniques, such as AM and FM.
In conclusion, the audio signals of TV
are amplitude modulated because this is the most efficient way to transmit them over long distances.