Answer

Correct Option: (ii) Improve signal-to-noise ratio (high-frequency boost)

Explanation

Pre-emphasis in FM is high-pass filtering (75 µs, cutoff ~2.1 kHz) at transmitter that boosts high-frequency components of $m(t)$ before modulation.

• FM noise PSD at detector output ∝ $f^2$ (parabolic) → high frequencies noisier.
• Boosting highs before TX → de-emphasis (low-pass) at receiver restores flat response while suppressing high-freq noise.

Result: SNR improvement ~10 dB. Complementary to de-emphasis at receiver.

Final Answer

Improve SNR → Option (ii) (high-frequency noise reduction). If option (i) “reduce low-frequency noise” is opposite.