Cloudy Corporation reported the following results for December: Amount Description Number of units sold Selling price per unit Cost of goods sold per unit (all variable) Variable selling expense per unit Fixed-selling expense Variable administrative expense per unit Fixed administrative expense 900 units $600 per unit $350 per unit $55 per unit $32,200 $42 per unit $26,600 The gross margin for December is: $137,700 B. $225,000 .c.$166,200 D. $452,700