The correct answer is B) Flue gases from the ship's boilers are used in some systems. Inert gas systems on tank vessels are used to maintain a non-flammable atmosphere in the cargo tanks. Flue gases from the ship's boilers are commonly used as the inert gas source, as they are readily available and cost-effective. This is in accordance with regulations set by the US Coast Guard and international maritime safety standards. The other options are incorrect - A) is false as the inert gas system actually helps prevent rusting by maintaining a non-oxidizing atmosphere, C) is false as helium is not the preferred inert gas (nitrogen or carbon dioxide are more commonly used), and D) is incorrect since only option B is true.