Final answer:
In the event of an accident with injury, death, or disappearance, you should file a report with local authorities and exchange insurance information, but not leave the scene immediately.
Step-by-step explanation:
If you are in an accident involving injury, death, or disappearance, the correct course of action would be to file a report with local authorities (option A). In many jurisdictions, there is a legal obligation to report such incidents to the police, especially when there is injury, death or someone is missing. Providing aid to the injured and ensuring safety is also paramount. It's important to also exchange insurance information with the other parties involved (option C), as this will be necessary for insurance claims and possible legal proceedings. It is imperative to not leave the scene immediately (option D) as this can result in legal consequences such as charges for hit-and-run. Notifying marina staff (option B) could be relevant if the accident occurred near a marina. However, reporting to authorities should always come first.