Explanation: J3E designates single-sideband (SSB) voice transmissions with a suppressed carrier. For effective voice communication, the modulating audio typically occupies a frequency range from approximately 300 Hz to 3100 Hz. When converted to an SSB signal, this results in a necessary occupied bandwidth of around 2.8 kHz. To prevent interference between adjacent SSB voice channels, a slightly wider channel spacing is assigned. A standard spacing of 3.0 kHz is commonly used, which accommodates the 2.8 kHz signal bandwidth and provides a small guard band on either side, ensuring clear reception and efficient spectrum utilization. Options A and B represent bandwidths suitable for very narrow-band digital modes, not voice. Option D's values are somewhat wider than the common and efficient standards for J3E voice.