Final answer:
The contra account among the given options is the accumulated depreciation.
Step-by-step explanation:
A contra account is an account that is offset against a related account in the financial statements. It is used to show the original amount and the reduction or offset for that amount. Accumulated depreciation is a contra account that is used to offset the value of an asset on the balance sheet.
For example, if a company has a building worth $100,000 and it has been using it for 10 years with a useful life of 20 years, the accumulated depreciation will be $50,000. This is because each year, $5,000 ($100,000 / 20) of the building's value is reduced, and after 10 years, the accumulated depreciation will be $50,000.