The correct answer is D) unless authorized by the Captain of the Port. The reasoning behind this is that under the regulations governing oil transfer operations, a person in charge is required to be present and in direct control of the oil transfer at all times. This person cannot be responsible for overseeing the transfer on more than one vessel simultaneously, unless specifically authorized by the Captain of the Port, who has the authority to grant such an exception. The other answer choices do not accurately reflect the regulatory requirements for oil transfer operations.