An 18-cm-long, 16-cm-wide, and 12-cm-high hot iron block (ρ = 7870 kg/m3, cp = 447 J/kg•ºC...

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

(a) 750ºC

(b) 830ºC

(c) 875ºC

(d) 910ºC

(e) 1000ºC