The balance sheet and income statement shown below are for Koski Inc. Note that the firm has no amortization charges, it does not lease any assets, none of its debt must be retired during the next 5 years, and the notes payable will be rolled over Balance Sheet (Millions of S) Assets 2018 $3,000 15,000 18,000 $36,000 $24,000 Cash and securities Accounts receivable Inventories Total current assets Net plant and equipment Total assets Liabilities and Equity Accounts payable Accruals Notes payable Total current liabilities $60,000 $18,630 8,370 6,000 $33,000 Long-term bonds Total liabilities Common stock Retained carnings Total common equity Total liabilities and equity $9,000 $42,000 $5,040 12,960 $18,000 $60,000 Income Statement (Millions of S) Net sales Operating costs except depreciation Depreciation Earnings before interest and taxes (EBIT) Less interest Earnings before taxes (EBT) 2018 $84,000 78,120 1,680 $4,200 900 Taxes $3,300 1,320 $1,900 Net income 500.00 $693.00 Other data: Shares outstanding (millions) Common dividends (millions of $) Intrate on notes payable & L-T bonds Federal plus state income tax rate Year-end stock price 40% $47.52 Refer to Exhibit 4.1. What is the firm's operating margin? Do not round your intermediate calculations. a. 5.85% b.4.10% c. 4.80% d. 4.55% 8.5.00%