Solution approach:  The amounts shown in the T-accounts represent the depreciation expense recorded for each year of the asset’s useful life (not the balance of the Accumulated Depreciation account as of the dates shown).  Thus, patterns can be determined directly from the numbers provided, without the necessity of making any calculations.

a. The units of production method is being used because the depreciation expense amounts do not demonstrate a clear pattern.  These amounts can be verified based on the machine’s productive capacity of 300,000 units and the actual production data provided for 2010-2014.