Which of the following statements about the end of an assets life is incorrect?

a. At end of life, the assets book value should equal its residual value

b. At end of life, the assets book value would equal zero if there is no residual value.

c. At end of life, the accumulated depreciation should equal the depreciable cost.

d. Assets are not to be depreciated below residual value unless the double-declining balance method is used.