On vessels over 100 gross tons, whose responsibility is it to ensure that all able seamen in the vessel's crew have the documents and qualifications required by law and regulation?

Correct Answer: Option C — Master of the vessel

Under 46 CFR 15.103, the Master is responsible for ensuring that all crew members, including Able Seamen, possess the necessary valid credentials and endorsements for their assigned duties. The Master must verify these documents prior to departure to ensure the vessel meets all safety and manning requirements.