Two very large parallel plates are maintained at uniform temperatures T₁ = 750 K and T₂ = 500 K and have emissivities ε₁ = 0.85 and ε₂ = 0.7, respectively. If a thin aluminum sheet with the same emissivity on both sides is to be placed between the plates in order to reduce the net rate of radiation heat transfer between the plates by 90 percent, the emissivity of the aluminum sheet must be
(a) 0.07

(b) 0.10

(c) 0.13

(d) 0.16

(e) 0.19