A steel billet of 2000 kg mass is to be cooled from 1250 K to 450 K. The heart released during this process is to be used as a source of energy. The ambient temperature is 303 K and specific heat of steel is 0.5kJ/kgK. The available energy of this billet is
(a) 490.44 MJ
(b) 30.95 MJ
(c) 10.35 MJ
(d) 0.10 MJ