What does the term "modulation index" refer to in amplitude modulation (AM)?

A) The ratio of the carrier frequency to the modulating frequency

B) The extent of variation of the carrier signal

C) The amplitude of the modulating signal

D) The frequency response of the modulator

Answer: B) The extent of variation of the carrier signal

Explanation: The modulation index in AM represents the degree to which the amplitude of the carrier signal is varied by the modulating signal, affecting the envelope and power distribution in the transmitted signal.