Which statement is true concerning the risk of collision?

The statement regarding the proper use of radar equipment to determine the risk of collision is true because radar is a crucial tool in navigation that enhances situational awareness, particularly in conditions where visibility is limited, such as fog or at night. The use of radar allows a vessel's crew to detect the presence of other vessels, assess their proximity, determine their course and speed, and make informed decisions to avoid collisions. This aligns with the broader responsibilities outlined in the nautical rules of the road, emphasizing the need for mariners to assess potential collision risks thoroughly and utilize any available technology to do so effectively.

The other statements do not accurately reflect best practices or requirements in maritime navigation. For instance, maintaining a constant speed for all vessels at all times does not account for the need to adjust speed based on proximity to other vessels or changing navigational circumstances. Assessing the risk of collision solely by visual means undermines the importance of using radar and other navigational aids, which can provide critical information that is not visible otherwise. Similarly, stating that radar equipment must not be used in fog contradicts standard maritime practice, where radar play an essential role in tracking and avoiding obstacles when visibility is poor.