The correct answer is A) Bunker "C". Bunker "C" is classified as a grade "E" combustible liquid according to the U.S. Coast Guard regulations. Grade "E" liquids have a flash point at or above 140°F (60°C), making them less volatile and safer to handle than more flammable liquids like gasoline (grade "B"). The other options, B) Very light naphtha, C) Benzene, and D) Most commercial gasoline, are all classified as more hazardous grade "B" or "C" flammable liquids with lower flash points.