A vessel's fire control plan shall do which of the following?

Correct Answer: Option C — have a duplicate set of plans permanently stored outside the deck house.

SOLAS Chapter II-2 requires a permanently stored duplicate set of fire control plans in a weather-tight enclosure outside the deckhouse. This ensures that shore-side firefighting teams can access critical information regarding the vessel's fire protection systems, boundaries, and equipment locations even if the main deckhouse is inaccessible.