Which of the following procedures is atest of control?

A.Agreed the sales invoices to the credit files to determine whether the customer had a credit file and has been approved for credit.

B.Computed the amount of depreciation expense based on the book value and the company's depreciation policy.

C.Verified units on hand in inventory by doing a full warehouse count at the balance sheet date.

D.Examined invoices to support the dollar amount of the additions to the fixed asset account during the year.