[单选题]
A thin metal plate of mass m is held at an absolute tempq6fj fh.gqci s 56k(k;eraturew0kdxuv2l wd l1u yny2. 9e*v2 T, in an enclosure of temperature vwl.n292 wdud yl*uvk1 0 2yex$T_s$
A. $\frac{σAT^4Δt}{m(Δt}$
B. $\frac{σA(T^4-T_s^4)Δt}{m(Δt}$
C. $\frac{2σAT^4Δt}{m(Δt}$
D. $\frac{2σA(T^4-T_s^4)Δt}{m(Δt}$