What frequency does AFC maintain in an FM receiver?

The correct answer is the intermediate frequency. In an FM receiver, the Automatic Frequency Control (AFC) system is responsible for ensuring that the receiver remains tuned to the correct frequency of the incoming signal. When the radio signal is received, it is typically first converted to an intermediate frequency through a process called frequency mixing. The intermediate frequency is a lower and fixed frequency that is easier to process. The AFC helps stabilize the tuning so that the receiver can effectively maintain the correct intermediate frequency in the presence of drift or other variations, ultimately ensuring better reception of the modulated signals.

The other options do not accurately reflect the role of AFC in an FM receiver. The carrier frequency refers to the original frequency of the signal being transmitted. The base frequency is not a standard term used in this context, and modulated frequency refers to the frequency after modulation has occurred, rather than the frequency that needs to be maintained during reception.