What should every vessel do to determine the risk of collision?

Answer: B — Use all available means appropriate to circumstances

To determine the risk of collision, every vessel should utilize all available means appropriate to the circumstances. This approach encompasses a range of techniques, including visual observation, radar, AIS (Automatic Identification System), sound signals, and any other navigational aids that may be at the crew's disposal. The reasoning behind this comprehensive method is that reliance on a single means, such as visual observation or radar alone, may not provide a complete picture of the surrounding traffic situation. Different environmental conditions, such as weather, visibility, and the nature of traffic in the area, might necessitate the use of multiple tools. For example, radar can be particularly useful in poor visibility, while visual observation is crucial in clear sight conditions. Evaluating the risk of collision effectively requires a thorough assessment using diverse resources to adapt to changing circumstances, ensuring a safer navigational decision.