What does "restricted visibility" mean?

"Restricted visibility" refers to a situation where the conditions impair a person's ability to see clearly, often due to environmental factors such as fog, rain, snow, or smoke. This condition may significantly reduce the range at which vessels can be seen, affecting navigation and safety on the water. It does not imply complete inability to see anything; rather, it indicates that visibility is compromised to varying degrees, which can pose risks for navigation and collision avoidance.

In contrast, the other options do not accurately define restricted visibility. Perfect visibility, as mentioned in the first choice, would indicate conditions that are the opposite of being impaired. The third choice, stating that no vessels can be seen at all, is too extreme and does not encompass the broad range of scenarios where visibility is merely limited. Lastly, the fourth option indicates a specific distance limitation (100 meters), which does not universally define restricted visibility, as it can vary widely based on the specific environmental conditions encountered.