U.S. regulations require that tank vessels handling grade B liquids shall have their cargo pumps separated from all sources of vapor ignition by which of the following?

Correct Answer: Option A — gas tight bulkheads

46 CFR mandates that cargo pumps for Grade B liquids must be isolated from machinery spaces or other ignition sources by gas-tight bulkheads. This physical barrier prevents flammable vapors from migrating into areas where electrical equipment or hot surfaces could trigger an explosion, ensuring the safety of the vessel.