In amplitude modulation, the sinusoidal carrier frequency is denoted by ωc and the signal frequency is denoted by ωm. The bandwidth (Δωm) of the signal is such that Δωm << ωc. Which of the following frequencies is not contained in the modulated wave?

Here ωc - ωm and ωc + ωm are respectively called the lower side and upper side frequencies. The modulated signal consists of the carrier wave of frequency ωc plus two sinusoidal waves each with a frequency slightly different from ωc, known as sidebands. The frequency spectrum of the amplitude modulated signal shows that the transmitted frequencies are between ωc - ωm and ωc + ωm. Hence ωm is not contained in the modulated wave.