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Question

$\begin{array}{1 1} (1) \text{In amplitude modulation the amplitude of the high frequency carrier wave is made to vary in proportion to the amplitude of the audio signal.} \\ (2)\text{In amplitude modulation the frequency of the high frequency carrier wave is made to vary in proportion to the amplitude of the audio signal.} \\ (3) \text{In frequency modulation the amplitude of the high frequency carrier wave is made to vary in proportion to the amplitude of the audio signal.} \\ (4) \text{In frequency modulation the amplitude of the high frequency carrier wave is made to vary in proportion to the frequency of the audio signal.} \end{array}$