A company that makes organic fertilizer has supplied the following data: Bags produced and sold 200,000 Sales revenue $1,560,000 Variable manufacturing expense 660,000 $ 448,000 Fixed manufacturing expense Variable selling and administrative expense $ 180,000 Fixed selling and administrative expense $214,000 58,000 Net operating income The company's unit contribution margin is closest to: Select one: a. $3.60 per unit b. $4.20 per unit c. $6.90 per unit d. $4.50 per unit