Demand for a certain product is forecast to be $800$ units per month, averaged over all $12$ months of the year. The product follows a seasonal pattern, for which the January monthly index is $1\mathrm{.}25.$ What is the seasonally$-$adjusted sales forecast for January?Question $23$ Select one:a$\mathrm{.}798\mathrm{.}75$ unitsb$\mathrm{.}640$ unitsc$\mathrm{.}83\mathrm{.}33$ unitsd$\mathrm{.}801\mathrm{.}25$ unitse$\mathrm{.}1000$ units