A vessel may depart from the rules if necessary to ______ immediate _______.

The correct response highlights that a vessel may deviate from navigation rules when it is necessary to avoid immediate danger. This principle is rooted in the fundamental concept of maritime safety, where the primary concern is the protection of life, vessels, and the marine environment.

When navigating, mariners must adhere to specific rules to ensure safe passage and prevent collisions. However, these rules are not absolute and must be flexible enough to account for unexpected and hazardous situations. If a vessel is faced with an imminent threat, such as another vessel's approach that could lead to a collision, the captain is compelled to take evasive action—thus deviating from the rules when it becomes essential to avoid immediate danger.

This situation emphasizes the importance of judgment and decision-making in navigation. The priority is always the safety of persons on board and others in the vicinity. Hence, the option selected aligns perfectly with maritime law and safe navigation practices that endorse taking necessary actions to mitigate risks when emergencies arise.

While other options might suggest various interactions or responses, they do not convey the urgency and necessity involved when a vessel must act to avert immediate peril.