In amplitude modulation, the sinusoidal carrier frequency used is denoted by ${\omega }_c$ and the signal frequency is denoted by ${\omega }_m$ . The bandwidth $\left(\mathrm{\Delta }{\omega }_m\right)$ of the signal is such that $\mathrm{\Delta }{\omega }_m\ll {\omega }_c$. Which of the following frequencies is not contained in the modulated wave?