Early in the accounting period, a customer paid $1,500 for services in advance of receiving them; Cash was increased and Unearned Service Fees was increased for $1,500. At the end of the accounting period, two-thirds of the services paid for had yet to be performed. What necessary adjustment would be made at the end of the period? Select one: a. BALANCE SHEET INCOME STATEMENT STOCKHOLDER'S EQUITY ASSETS = EXPENSE LIABILITIES (Unearnd Service Fees) -1,000 REVENUE (Service Fees Earned) +1,000 +1,000 O b. ASSETS = BALANCE SHEET INCOME STATEMENT LIABILITIES + STOCKHOLDER'S EQUITY REVENUE EXPENSE (Unearnd Service Fees) (Service Fees Earned) +1,000 1,000 - 1,000 C. BALANCE SHEET INCOME STATEMENT STOCKHOLDER'S EQUITY + ASSETS = LIABILITIES (Unearnd Service Fees) ( 500 REVENUE EXPENSE (Service Fees Earned) ) -500 -500 O d. BALANCE SHEET INCOME STATEMENT STOCKHOLDER'S EQUITY ASSETS = EXPENSE LIABILITIES (Uneard Service Fees) -500 REVENUE (Service Fees Earned) -500 +500