问问这道题怎么理解谢谢

问题如下：

Question Changing the estimates of the salvage value of capital assets is the least effective way to manage earnings during the life of an asset for companies whose method of depreciation is:

选项：

A.straight-line.

B.units-of-production.

C.double-declining balance.

解释：

1. Incorrect. The straight-line method calculates depreciation on the net cost of the assets. Changing the salvage value will change the depreciation deduction and thereby affect earnings.

2. Incorrect. The units-of-production method calculates depreciation rate based on the net cost of the assets. Changing the salvage value will change the depreciation rate and thereby affect earnings.

3. Correct. The double-declining balance depreciation method applies the rate to the gross cost of the equipment, so a change in the salvage assumption will have no effect on earnings until the net book value reaches the estimated salvage value, at which point the company ceases to take depreciation on the asset.

• describe accounting methods (choices and estimates) that could be used to manage earnings, cash flow, and balance sheet items