A vessel underway and making way in fog shall sound a prolonged blast every:

Answer: B — two minutes

When a vessel is underway and making way in fog, it is required to sound a prolonged blast every two minutes. This rule serves as a warning signal to other vessels in the area, indicating the presence of the navigating vessel to prevent collisions in reduced visibility conditions. The rationale behind sounding a prolonged blast is to ensure that vessels can communicate their presence to others, as visibility is often severely compromised in fog. By adhering to this established interval, vessels contribute to overall safety and situational awareness on the water. Understanding the timing of warning signals is crucial for mariners because it helps maintain a standard practice that all vessel operators can recognize, which enhances safety for everyone navigating in challenging environmental conditions.