The correct choice is (b) 150 tonnes/hr & above
Explanation: Feed water from the hot-well is forced through the economizer tubes. The hot water enters the radiant section of the evaporator tubs and then passes through convective section of the evaporator tubes. Since the boiler has no drum, thee steam generated in the evaporator enters the super heater tube where it is heated above the critical pressure. So the Steam rising capacity of the boiler is 150 tonnes/hr & above.