According to the Navigation Rules, a risk of imminent collision exists in which situation?

The situation in which the course of an approaching vessel does not change is indicative of a risk of imminent collision. This is because when one vessel continues on its set path without altering its course, it creates a scenario where the vessels are on a converging path. If both vessels maintain their current courses, they are likely to meet at a point where a collision could occur. This situation requires one or both vessels to take action to avoid an accident.

The other options do not necessarily indicate an imminent collision risk. When vessels approach from different directions, they may have defined navigation rules that dictate how and when to yield, thus potentially avoiding a collision. A vessel that has the right of way does not guarantee an imminent risk since the other vessel may yield appropriately. Lastly, sudden changes in weather conditions can affect visibility and vessel handling, but they do not directly indicate that two vessels are on a collision course unless combined with factors such as their courses being unaltered.