Explanation: Pre-emphasis is a technique used in FM transmission to improve the signal-to-noise ratio of the recovered audio. Noise in FM systems tends to have a greater impact on the higher modulation frequencies. To combat this, the audio's *higher modulation frequencies* are selectively boosted before transmission. This boost is typically a *6 dB per octave* increase. By increasing the amplitude of these higher frequencies, they become stronger relative to the inherent high-frequency noise that will be introduced during transmission. At the receiver, a complementary circuit called de-emphasis reduces these boosted frequencies back to their original levels. In doing so, it also reduces the high-frequency noise that was picked up during transmission, effectively lowering the noise floor and improving the overall audio clarity. Options A, C, and D are incorrect because pre-emphasis specifically targets *higher* modulation frequencies, not lower ones, and the standard boost rate is 6 dB per octave, not 3 dB.