Pre emphasis is done2 pointsFor boosting of modulating signal voltageFor modulating signals at higher frequenciesIn FM before modulationAll of the above

Pre-emphasis is done for several reasons:

1. Boosting of Modulating Signal Voltage: Pre-emphasis is used to increase the strength of the higher frequency components of the signal. This is done to balance the signal because the amplitude of a frequency modulated signal decreases with frequency.

2. For Modulating Signals at Higher Frequencies: Pre-emphasis is used to improve the signal-to-noise ratio for higher frequency signals. This is because higher frequency signals are more susceptible to noise. By boosting these signals, the effect of noise is reduced.

3. In FM Before Modulation: Pre-emphasis is applied to the modulating signal before it is used to modulate the carrier in frequency modulation. This is done to improve the overall signal-to-noise ratio of the system.

4. All of the Above: All the above points are valid reasons for using pre-emphasis in a communication system. Therefore, the answer is "All of the above".