One multiple choice question

Which of the following is not accounted for as a change in accounting principle? Select one: a. A change in the estimated useful life of plant assets. b. A change from accelerated method to straight line method of depreciation. O c. A change from deferring and amortizing R&D expenditures to expensing those as incurred. d. A change in inventory cost-flow assumption from average cost to FIFO. e. a and b f. a, b, and c