The balance sheets at the end of each of the first two years of operations indicate the following: 2012 2011 Total current assets $600,000 $560,000 Total investments 60,000 40,000 Total property, plant, and equipment 900,000 700,000 Total current liabilities 125,000 65,000 Total long-term liabilities 350,000 250,000 Preferred 9% stock, $100 par 100,000 100,000 Common stock, $10 par 600,000 600,000 Paid-in capital in excess of par-common stock 75,000 75,000 Retained earnings 310,000 210,000 If net income is $115,000 and interest expense is $30,000 for 2012, what is the rate earned on stockholders' equity for 2012 (round percent to one decimal point)? Select one: a. 12.4% b. 11.1% c. 10.6% d. 14.0%