Solar innovations corporation bought a machine at the beginning of the year at a cost of $22,000. the estimated useful life was five years, and the residual value was $2,000. assume that the estimated productive life of the machine is 10,000 units. expected annual production was: year 1, 2,000 units; year 2, 3,000 units; year 3, 2,000 units; year 4, 2,000 units; and year 5, 1,000 units.

a) straight-line
b) units-of-production
c) double-declining-balance