What characteristic differentiates a QAM channel from an analog TV channel?

A QAM (Quadrature Amplitude Modulation) channel differs from an analog TV channel primarily due to its ability to transmit more data within the same bandwidth by leveraging both amplitude and phase variations. When accounting for equal amplitude and bandwidth comparisons, the power level of a QAM channel can indeed be higher. This characteristic allows QAM to encode more bits per symbol compared to analog modulation techniques, which primarily rely on amplitude modulation and do not utilize phase.

This efficient utilization of resources results in higher data throughput capabilities for QAM channels, making them preferable in digital communications. Furthermore, QAM can support higher-order modulation schemes, thereby increasing the number of states that can be transmitted simultaneously. This enhanced effectiveness in transmitting information makes option C the correct choice, highlighting the distinct advantage of QAM in data transmission over analog channels, which traditionally do not optimize for power and bandwidth in the same manner.