Explanation: The RF gain control directly adjusts the amplification provided by the receiver's RF amplifier stage, which is located early in the receiver chain, before the signal is converted to intermediate frequency (IF) or detected. When you reduce the RF gain, you decrease the amount of amplification applied to the incoming weak radio frequency signals. A receiver's sensitivity is its ability to pick up and process weak signals. By reducing the early amplification, the receiver becomes less capable of detecting and adequately processing these faint signals, effectively making it less sensitive. This is often done to prevent strong signals from overloading the receiver's front end. A) Degenerative feedback is an internal design characteristic, not something adjusted by a user-controlled RF gain knob. B) While reducing RF gain will lower overall volume, its primary effect is on the RF stage's ability to amplify weak signals, which is a matter of sensitivity, not just audio volume adjustment. Volume control typically adjusts the audio signal *after* detection. C) Coupling between stages is a fixed design parameter, not something that an RF gain control adjusts. The gain control changes the amplification *within* the stages, not the connections *between* them.