When underway with a tow, you are required to notify the Coast Guard in which casualty situation?

Correct Answer: Option B — Accidental stranding or grounding

46 CFR § 4.05-1 requires immediate notification to the nearest Coast Guard Marine Safety Office for specific casualties, including accidental groundings. While minor incidents may not always require a formal report, a grounding is a significant event that necessitates official USCG awareness and potential investigation into the vessel's safety.