When deciding whether or not to discontinue a product line, which of the following is true? a. Allocated common company costs are unavoidable costs and therefore irrelevant to the decision. b. Common company costs will be incurred whether the product line is dropped or not and are therefore relevant to making the decision. c. Only the fixed portion of common company costs is relevant to the decision of dropping a product line. d. As long as common company costs are allocated based on sales revenue they are relevant to the decision of dropping a product line