The correct answer is B) Refuse to sign the man on articles until authorized by the Coast Guard. This is the correct answer because when a merchant mariner's document is suspected to have been tampered with, the proper procedure is to refuse to sign the individual on until the Coast Guard can verify the validity of the document. Signing on the individual without authorization could be considered complicity in the unauthorized use of a federal document. The other options, such as confiscating the document or notifying the FBI, are not the appropriate first steps in this situation. The responsible action is to refuse to sign on the individual and contact the Coast Guard to investigate the document before proceeding further.