Penetrations and openings in watertight bulkheads in a small passenger vessel less than 100 gross tons must __________.

Correct Answer: Option D — All of the above

46 CFR 179.310 requires that watertight bulkheads maintain their integrity. Penetrations must be kept high and inboard to minimize flooding risk, and all openings must be fitted with watertight closures. Sluice valves are strictly prohibited because they create a direct path for progressive flooding between compartments during an emergency.