In a job costing system, $$45,000$ has been charged to a job $($$$25,000$ of direct materials, $$10,000$ direct labor, and $$10,000$ applied overhead$).$ The job yields $500$ units of a product, of which $100$ are rejected by the entity as spoiled with no salvage value. The cost of the spoilage is determined to be $$9,000.$ If the entity wishes to use this job as the basis for setting a spoilage standard for comparison with future work, the conceptually superior way to express the spoilage rate is

A$\mathrm{.}20\%$ of total inputs.

B$\mathrm{.}36\%$ of material inputs.

C$\mathrm{.}25\%$ of good outputs.

D$\mathrm{.}90\%$ of labor inputs.