Michael Purchased Two Vehicles for His Business on 1 January

Michael purchased two vehicles for his business on 1 January 2011.These vehicles cost $50,000 each and have a useful life of 5 years with an expected residual of $20,000 each.The adjusting entry for depreciation on 31 December 2011,using the straight-line method,is:

A) Dr Accumulated Depreciation $6000; Cr Depreciation Expense $6000
B) Dr Depreciation Expense $6000; Cr Accumulated Depreciation $6000
C) Dr Accumulated Depreciation $12 000; Cr Depreciation Expense $12 000
D) Dr Depreciation Expense $12 000 Cr Accumulated Depreciation $12 000