ANS:B - Outgoing flue gases.

The account that typically accounts for the maximum loss of energy in a coal-fired boiler is: Outgoing flue gases. In a coal-fired boiler, outgoing flue gases carry a significant amount of heat energy that is not utilized and is lost to the environment. These flue gases contain high-temperature exhaust gases resulting from the combustion of coal and other fuels in the furnace. The heat energy carried by these flue gases represents a substantial portion of the total energy input to the boiler. While incomplete combustion of fuel, radiation heat losses, and unburnt carbon in ash also contribute to energy losses in a coal-fired boiler, the energy carried away by outgoing flue gases is typically the largest component of energy loss. Inefficient combustion processes, incomplete utilization of fuel, and heat losses through radiation and unburnt carbon in ash contribute to energy losses but may not account for as much energy loss as the flue gases. Therefore, among the options provided, outgoing flue gases account for the maximum loss of energy in a coal-fired boiler.