NAVTEX broadcasts are sent:

Correct Answer: Option A — In categories of messages indicated by a single letter or identifier.

NAVTEX broadcasts are categorized by specific subject indicators (B2 characters) that allow receivers to filter incoming data. These categories include navigational warnings, weather forecasts, and search and rescue information, ensuring mariners receive prioritized MSI relevant to their operational requirements as established by the IMO GMDSS carriage requirements.