What action must a give-way vessel take when necessary?

Answer: B — Take early and substantial action to keep clear

The give-way vessel is required to take early and substantial action to keep clear of the stand-on vessel when necessary. This is a crucial responsibility under the COLREGs, as the give-way vessel must ensure that there is no risk of collision. By taking prompt and significant action—such as altering course or speed—it can effectively avoid a collision scenario if the stand-on vessel is not able to maneuver. In contrast, simply waiting for the stand-on vessel to take action does not fulfill the give-way vessel's obligation to prevent incidents. Additionally, signaling to the other vessel or merely adjusting speed without changing course could result in confusion or insufficient maneuverability, potentially leading to a dangerous situation on the water. Therefore, the most effective and responsible action is to make a deliberate and noticeable maneuver to maintain safety and compliance with navigational rules.