Smith & Sons Balance Sheet As of December 31 Cash $80,000 Current liabilities $160,000 Accounts receivable 160,000 Bonds payable 240,000 Inventory 260,000 Common Stock 400,000 Plant assets (net) 500,000 Retained earnings 200,000 Total assets $1,000,000 Total liabilities and stockholders' equity $1,000,000 Sales revenue for the year was $1,600,000, gross profit was $640,000, and net income was $72,000. One year ago, accounts receivable were $152,000, inventory was $220,000, total assets were $920,000, and stockholders' equity was $520,000. What was the firms return on sales for the year? Select one: 6.0 percent 4.5 percent 5.0 percent 9.0 percent