Accumulated depreciation and depreciation expense are classified, respectively, as

a. asset, contra liability
b. expense, contra asset
c. contra asset, expense
d. revenue, asset

C. contra asset, expense

Explanation:

The depreciation is an expenditure indicating a decline in the value of the fixed assets due to wear and tear, obsolescence, use, time period, etc. It's shown on the income statement debit side This is a non-cash item which has no effect on the cash balance.

Whereas the accumulated depreciation is an contra asset which reduce the asset balance. It records the depreciation in arrears and reported in the asset side of the balance sheet

Like

Equipment                                    ()

Less - Accumulated depreciation ()

Net value of equipment               ()

A (the entire green box): chemical equation

B (the blue box): reactants

C (the arrow): reacts to form

D (the purple box): products