What must be carried on board every oil tanker of 150 GT and every ship of 400 GT or more?

The correct answer is that a Shipboard Oil Pollution Emergency Plan (SOPEP) must be carried on board every oil tanker of 150 gross tons (GT) and every ship of 400 GT or more. This requirement is rooted in international maritime regulations, specifically those established by the International Convention for the Prevention of Pollution from Ships (MARPOL). The SOPEP is essential for providing a clear plan of action in the event of an oil spill, ensuring that the crew is prepared to minimize environmental damage and respond effectively to any emergencies related to oil pollution.

By mandating the existence of a SOPEP, authorities ensure that vessels are equipped with the necessary guidelines and procedures to manage oil spill incidents, which is a critical aspect of marine environmental protection. Ships are required to have their SOPEP readily available and understood by the crew, which allows for prompt and coordinated responses should an oil pollution emergency occur.

The other options, while relevant to ship operations, do not carry the same regulatory requirement for all oil tankers and larger ships. A waste disposal certificate, for instance, pertains specifically to the management of waste onboard, but it is not universally required in the same way as a SOPEP. An emergency communication system is a crucial aspect