$7-1.$ If the $BO{D}_5$ and ultimate BOD of a municipal wastewater are $200m\frac{g}{L}$ and $457m\frac{g}{L}$ respectively, what is the reaction rate constant?

a$.0\mathrm{.}265d^{-1}$

b$.0\mathrm{.}050d^{-1}$

c$.0\mathrm{.}115d^{-1}$

d$.0\mathrm{.}165d^{-1}$