Question 62General Subjects - QMED

The correct answer is A) Combustion gases flow through the tubes. In a fire-tube boiler, the hot combustion gases from the furnace flow through the tubes that are submerged in the water. This heats the water, which in turn generates steam. The flames do not impinge on the tubes directly (option B is incorrect), and the combustion does not occur inside the tubes (option C is incorrect). The water flows around the outside of the tubes, not through them (option D is incorrect). The flow of combustion gases through the tubes is the defining characteristic of a fire-tube boiler, which makes option A the correct answer.