The correct answer is B) steel or equivalent material. The reason for this is that the US Coast Guard regulations for small passenger vessels require paint and oil lockers to be constructed of or lined with steel or an equivalent material that is fire-resistant. This is to prevent the spread of fire and limit the potential for fuel or other flammable materials to ignite. The other options, such as fiberglass, sheetrock, or marine plywood, do not provide the same level of fire protection required by the regulations.