When originally purchased, a vehicle had an estimated useful life of 9 years. The vehicle cost $21,000 and its estimated salvage value is $2,000. After 4 years of straight-line depreciation, the asset's total estimated useful life was revised from 9 years to 6 years and there was no change in the estimated salvage value. The depreciation expense in year 5 equals (round depreciation per year to a whole number):

$5,528

$6,278

$5,778

$5,278

$5,178