Elizabeth Morrow operates Oriole Riding Academy, Inc. The academy's primary sources of revenue are riding fees and lesson fees, which are provided on a cash basis. Elizabeth also boards horses for owners, who are billed monthly for boarding fees. In a few cases, boarders pay in advance of expected use. For its revenue transactions, the academy maintains these accounts: Cash, Accounts Receivable, Unearned Service Revenue, and Service Revenue. The academy owns 10 horses, a stable, a riding corral, riding equipment, and office equipment. These assets are accounted for in the following accounts: Horses, Buildings, and Equipment. The academy employs stable helpers and an office employee, who receive weekdy salaries. At the end of each month, the mail usually brings bills for advertising, utilities, and veterinary service. Other expenses include feed for the horses and insurance. For its expenses, the academy maintains the following accounts: Supplies, Prepaid Insurance, Accounts Payable, Salaries and Wages Expense, Advertising Expense, Utilities Expense, Maintenance and Repairs Expense, Supplies Expense, and Insurance Expense. Elizabeth's s sole source of personal income is dividends from the academy. Thus, the corporation declares and pays periodic dividends. To account for stockholders' equity in the business and dividends, two accounts are maintained: Common Stock and Dividends. During the first month of operations, an inexperienced bookkeeper was employed. Elizabeth asks you to review the following eight entries of the 50 entries made during the month. In each case, the explanation for the entry is correct. May 1 Cash 5 Unearned Service Revenue (Issued common stock in exchange for $12,300 cash) Cash Service Revenue (Received $210 cash for lesson fees) 7 Cash Service Revenue (Received $410 for boarding of horses beginning June 1) Supplies Expense Cash 12,300 12,300 210 210 410 410 1,230 1230