The account that is not a revenue account is "purchases."
Revenue accounts are used to track all the income earned by a company. The four options provided in the question are all related to revenue except for "purchases." Purchases refer to the amount of money spent by a company to acquire goods or services for resale or use in the operation of the business. It is an expense account and not a revenue account.
In simpler terms, revenue accounts are for tracking money earned by a company, while the purchases account is for tracking money spent by the company.