At December 31, Marker reported the following items: cash, $7,500; inventory, $3,900; accounts payable, $5,900; accounts receivable, $3,100; common stock, $6,000; property, plant, and equipment, $10,500; interest payable, $1,600; retained earnings, $11,500. What is Marker's stockholders' equity? a. $7,500 Ob. $17,500 c. $25,000 Od. $19,100