In accordance with the international MARPOL Annex VI regulations, what is a permissible alternative to burning oil residue sludge in an appropriate incinerator?

Correct Answer: Option A — The oil sludge residue may be burned in a boiler OR engine, AND it may be burned only in unrestricted waters (other than in port, in harbors, or estuaries).

MARPOL Annex VI allows oil residue sludge to be burned in boilers or main engines as a fuel supplement. However, this practice is restricted to unrestricted waters and is prohibited while the vessel is in port, harbors, or estuaries to prevent localized air pollution in sensitive coastal areas.