Which of the following is a valid type of distress signal?

Answer: B — dye marker in the water

A dye marker in the water is indeed a valid type of distress signal. It is a recognized method used to indicate a need for assistance. These markers are generally brightly colored and spread out in the water, making them easily visible from a distance, especially by aircraft or rescue vessels. This method is effective in search and rescue operations as it visually marks an area for rescuers to focus on, signifying that someone in that vicinity is in possible danger. The other options do not meet the established criteria for distress signaling. While a whistle of three blasts may indicate an alert in certain situations, it is not universally recognized as a distress signal. A single loud bang can also be misleading, as it may not clearly convey a state of emergency. Similarly, a quick wave from a vessel could easily be misinterpreted as a normal greeting instead of a call for help. Therefore, the dye marker stands out as a clear, effective, and recognized method of signaling distress.