Thomas Company acquired machinery on January 2, 2016, which it depreciated under the straight-line method with an estimated life of fifteen years and no salvage value. On January 1, 2020, Thomas estimated that the remaining life of this machinery was six years with no salvage value. How should this change be accounted for by Thomas?

Group of answer choices

by continuing to depreciate the machinery over the original fifteen year life

as a prior period adjustment

as a change in accounting principle in 2020

by setting future annual depreciation equal to one-sixth of the machinerys book value on January 1, 2020