Myster Co purchased equipment for $25 000. Originally it had an estimated useful life of 4 years and a residual value of $5000. At the beginning of the 4th year of the equipment's life the estimated useful life was extended by a further three years and the residual value was reduced to zero. Myster Co uses the straight-line method to depreciate its equipment. At the end of year 4, how much depreciation should be recorded for the computer? a. $4 000 b. $5 000 c. $2 500 d. $1 250