Two large diffuse gray parallel plates, separated by a small distance, have surface temperatures of $400$ $K$ and $300$ $K$. If the emissivities of the surfaces are $0.8$ and the Stefan-Boltzmann constant is $5.67$ × $10^{-8}$ $W$/$m^2$ $K^4$, the net radiation heat exchange rate in $kW$/$m^2$ between the two plates is
- $0.66$
- $0.79$
- $0.99$
- $3.96$