What is the amount of the depreciation expense that be recorded for the year ended year four ?

A corporate purchased a machine for six thousand dollars on january1 ,year1 , for estimated useful life six years with no salvage value . The machine was been depreciated on a straight-line basis . On january1, year four the corporate determined that the machine had an estimated life of eight years from the date of acquisition . An accounting change was made was made in year four .

1) seventy five thousand $ .

2) zero .

3) sixty thousand $ .

4) one hundred thousand $.

source cpa ex.