Explanation: For CW (Continuous Wave) reception, a tuned audio frequency amplifier acts as an audio filter. CW signals, once detected by the receiver, produce a specific audio "beat frequency" (e.g., 700 Hz). By tuning the amplifier to pass only a narrow range of audio frequencies centered around this desired beat frequency, it significantly attenuates or rejects unwanted audio signals, noise, and interference from other frequencies outside its passband. This selective amplification improves the signal-to-noise ratio, making the desired CW signal much clearer and easier to copy. Therefore, it provides a reduction in interference from unwanted signals. Option B is incorrect because a tuned amplifier is designed to *amplify* the desired beat frequency, not attenuate it. Attenuating the desired signal would make it harder to hear. Since B is incorrect, C and D are also incorrect.