How do fire-tube boilers differ from water-tube boilers, and what is a typical application for each?

How do fire-tube boilers differ from water-tube boilers, and what is a typical application for each?

• A. Fire-tube boilers have hot combustion gases inside tubes surrounded by water; simple, compact, used for smaller capacities.
• B. Fire-tube boilers have water inside tubes with hot gases around them; suited for high pressure and large capacities.
• C. Water-tube boilers are simple, compact, used for smaller capacities.
• D. Water-tube boilers have hot combustion gases inside tubes surrounded by water; suited for high pressure and large capacities.

Answer: (A)