Explanation: Pre-emphasis in the transmitter intentionally boosts higher audio frequencies before modulation. This is done because higher frequencies in speech or music often have lower average power and are more susceptible to noise and interference during transmission. De-emphasis in the receiver audio stage performs the inverse function: it attenuates these same higher frequencies *after* demodulation. When properly matched with the transmitter's pre-emphasis, this process accomplishes two key goals: 1. **Flat Audio:** The attenuation at the receiver precisely reverses the boost applied at the transmitter, restoring the original audio frequency balance and ensuring natural-sounding, "flat" audio. 2. **Noise Reduction:** Critically, the de-emphasis filter also significantly attenuates the high-frequency noise that was introduced during transmission. Since the desired high-frequency audio was boosted before transmission, it remains strong enough even after de-emphasis, while the unwanted noise is significantly reduced, improving the overall signal-to-noise ratio. Therefore, option B is correct because the combined effect of pre-emphasis and de-emphasis results in both flat audio reproduction and effective noise reduction. Option A is incorrect because it misses the crucial benefit of noise reduction. Option C is incorrect as the process serves a vital purpose. Option D describes the function of squelch or VOX, which is unrelated to de-emphasis.