Which of the following statements about a process costing system is incorrect?

A、Inaprocesscostingsystem,thereisawork-in-progressaccountforeachprocessingdepartment.;
B、Inaprocesscostingsystem,equivalentunitsareseparatelycomputedformaterialsandforconversioncosts.;
C、Inaprocesscostingsystem,overheadcanbeunder-oroverapplied,justasinjob-ordercosting.;
D、Inaprocesscostingsystem,materialscostsaretracedtounitsofproducts.