Final answer:
Sales is not a contra account; it is a revenue account reflecting income earned, in contrast to contra accounts that reduce the balance of related accounts.
Step-by-step explanation:
The account that would not be classified as a contra account is A. Sales. Contra accounts are accounts with a balance that is opposite to the normal balance of its related accounts. Sales and return allowances, accumulated depreciation, and sales discounts are all examples of contra accounts because they reduce the balance of their related accounts. However, Sales is a revenue account that records the income earned by a company and does not act to reduce the balance of another account.