What is done to prevent the output of the QAM modulator from experiencing intersysmbol interference (ISI) and exceeding the 6 MHz bandwidth?
a. Apply pulse shaping to the input data before modulation
b. Use a Nyquist filter to avoid overlapping symbols in the frequency domain
c. Implement adaptive equalization at the receiver to compensate for channel distortion
d. Utilize frequency equalization to ensure that the QAM modulator output stays within the 6 MHz bandwidth limit