Correct option is A
In a thermal power plant, fire tube and water tube boilers are classified based on tubular heating surface. This classification depends on whether the hot gases pass through the tubes or the water passes through the tubes.
Fire Tube Boilers: In fire tube boilers, hot combustion gases pass through tubes, and the water to be heated surrounds these tubes.
Water Tube Boilers: In water tube boilers, water flows through the tubes, while the hot combustion gases surround the tubes.
