A surface absorbs 10 percent of radiation at wavelengths less than 3 mm and 50 percent of radiation at wavelengths greater than 3 μm. The average absorptivity of this surface for radiation emitted by a source at 3000 K is
(a) 0.14

(b) 0.22

(c) 0.30

(d) 0.38

(e) 0.42