A body at a temperature of 728°C and having surface area 5 cm2, radiates 300 J of energy each minute. The emissivity is [Given Boltzmann constant : =5.67×10–8 Wm–2 K–4]

(a) e = 0.18

(b) e = 0.02

(c) e = 0.2

(d) e = 0.15