A small passenger vessel's Official Number must be marked___________.

Correct Answer: Option C — or mounted so its alteration, removal, or replacement would be obvious

Per 46 CFR 67.121, the Official Number must be permanently marked on a clearly visible interior structural part of the hull. The marking must be done in a manner that makes any alteration, removal, or replacement obvious, ensuring the vessel's identity remains tamper-evident throughout its operational life.