The allocation of manufacturing overhead costs to products is difficult because a. most products produced by a company are very similar so that distinguishing between the individual products becomes difficult. b. many manufacturing overhead costs are period expenses and are thus not easily categorized in a particular production cycle. c. since all manufacturing overhead costs are indirect expenses, it is not possible to identify any of them with a particular product. d. it is often difficult to determine how much of a particular overhead cost is consumed by individual products