In accordance with the international MARPOL Annex VI regulations, the sulphur content of any fuel oil used on board ships shall not exceed what percentage by weight?

Correct Answer: Option C — 4.5%

MARPOL Annex VI, Regulation 14, historically established a global cap of 4.5% sulphur content by weight for marine fuel oils. While subsequent amendments have significantly lowered this limit to 0.50% globally, this specific examination question reflects the legacy regulatory framework established during the initial implementation of the Annex.