The number or name of a tank barge shall be __________.

Correct Answer: Option C — displayed at the highest point of the barge's hull such that it can be seen from either side

Under 46 CFR 32.05-5, the name or official number of a tank barge must be clearly displayed at the highest point of the vessel's hull or superstructure so that it is easily visible from either side, facilitating rapid identification by authorities.