At $250C$ the diffusion and activation energy for $W$ in Au are: $D(250C)=8\mathrm{.}9{10}^{-11}\frac{m^2}{s}$ and $Q=38\mathrm{.}5k\frac{J}{m}ol.$ What is the diffusion coefficient at $745C?$

$=8\mathrm{.}314\frac{J}{m}ol-K?$

$6\mathrm{.}59{10}^{-9}\frac{m^2}{s}$

$8\mathrm{.}05{10}^{-7}\frac{m^2}{s}$

$4\mathrm{.}30{10}^{-10}\frac{m^2}{s}$

$7\mathrm{.}21{10}^{-8}\frac{m^2}{s}$