Your vessel has run aground and upon taking fuel oil tank soundings, you find that a fuel tank level has increased. You therefore should suspect __________.

Correct Answer: Option D — a crack in the hull portion of the fuel tank

An increase in fuel oil tank levels following a grounding indicates that the external hydrostatic pressure is forcing seawater into the tank through a hull breach. This is a clear sign of structural failure in the tank boundary, requiring immediate investigation to prevent environmental pollution and fuel contamination.