An 18-cm-long, 16-cm-wide, and 12-cm-high hot iron block ( = 7870 kg/m 3 , c p =

An 18-cm-long, 16-cm-wide, and 12-cm-high hot iron block (ρ = 7870 kg/m³, c_p = 447 J/kg · K) initially at 20°C is placed in an oven for heat treatment. The heat transfer coefficient on the surface of the block is 100 W/m² · K. If it is required that the temperature of the block rises to 750°C in a 25-min period, the oven must be maintained at
(a) 750°C

(b) 830°C

(c) 875°C

(d) 910°C

(e) 1000°C