On board a small passenger vessel, fuel tank vents should __________.

Correct Answer: Option D — All of the above

46 CFR 25.40-1 mandates that fuel tank vents must be connected at the highest point, installed with an upward gradient to prevent liquid traps, and fitted with a corrosion-resistant flame screen. These measures collectively prevent fuel accumulation, ensure proper venting, and mitigate the risk of flashback into the fuel tank.