What is the baud rate at which the initial tones CNG and CED travel?

The correct baud rate for the initial tones CNG (Calling Tone) and CED (Call Establishment Descriptor) is 300bps. This low baud rate is notable because it was commonly used in early modem communications, particularly in relation to fax machines and certain telecommunication standards during their developments.

CNG and CED tones are part of the signaling process used to establish a connection over telephone lines. At 300bps, these tones provide a simple and effective way to signal readiness for communication between devices. Higher rates were introduced later for data transmission, but CNG and CED specifically reference the early modem standards where 300bps was the recognized rate for such signaling.

In the context of the other given choices, higher baud rates represent advancements in technology for data transmission but do not apply to the specific tones used for CNG and CED. These tones were established before the introduction of higher speed modems, highlighting the significance of 300bps in historical communication standards.