Why is it not appropriate to use "number of units" as the allocation base when calculating the POHR rate? OA. Each unit is unique and can use varying amounts of the true cost driver. OB. It is impossible to estimate the number of units the company will produce throughout the year. C. Each job can have different number of units in the job. OD. It is appropriate to use "number of units" as the allocation base when calculating the POHR rate. OE. The formula to allocate MOH to a job does not include "number of units."