The correct answer is C) Coal should be surface ventilated to remove methane gas. This is correct because coal can generate methane gas, which is a safety hazard if allowed to accumulate in the ship's cargo holds. Proper surface ventilation is required to disperse the methane and prevent the buildup of explosive gas concentrations. The other options are incorrect - A) is false as anthracite coal actually generates less methane than bituminous coal, B) is not necessary as long as proper ventilation is provided, and D) is incorrect as methane itself does not directly cause corrosion of the ship's structure.