A 2-kW baseboard electric resistance heater in a vacant room is turned on and kept on for 15 min. The mass of the air in the room is 75 kg, and the room is tightly sealed so that no air can leak in or out. The temperature rise of air at the end of 15 min is
(a) 8.5°C
(d) 33.4°C
(b) 12.4°C
(e) 54.8°C
(c) 24.0°C