Which of the following represents a valid 22-MHz ITU Channel?

The correct choice identifies a valid 22-MHz ITU channel designation, which is essential for maritime communication within the GMDSS framework. The designation "HF Ch-2206" refers to a high-frequency (HF) communication channel specifically allocated within the 22 MHz band for ship-to-ship and ship-to-shore communication. This channel is part of the International Telecommunication Union (ITU) frequency allocations for maritime use, ensuring that vessels can communicate effectively over long distances.

In contrast, the other choices do not pertain to a valid 22-MHz ITU channel as recognized in maritime communication. VHF channels operate in a different frequency range entirely, making "VHF Ch-22" incorrect for this context. "Ch-22A VTS" refers to a vessel traffic service channel, which serves a different purpose and does not indicate a specific 22-MHz ITU channel. Lastly, "Ch-70" is designated for Digital Selective Calling (DSC) only and does not represent a traditional voice communication channel, further distinguishing it from the specific frequency mentioned in the correct answer.