Which of the Following Is a Change in an Accounting

Which of the following is a change in an accounting estimate?
I. A change from straight line depreciation to an accelerated depreciation method.
II. A change in estimated salvage value of depreciable asset.
III. A change in estimated useful life of an asset.
IV. Recording depreciation for the first time on machinery purchased five years ago.

A) I, II, III and IV
B) II, III and IV
C) I, III and IV
D) II and III