Bruce Corporation makes four products in a single facility. These products have the following unit product costs:

ProductsABCDDirect materials$16.50$20.40$13.40$16.10Direct labor18.5021.9016.3010.30Variable manufacturing overhead5.306.509.006.00Fixed manufacturing overhead28.4015.3015.4017.40Unit product cost68.7064.1054.1049.80

Additional data concerning these products are listed below.

ProductsABCDGrinding minutes per unit2.451.551.150.75Selling price per unit$83.20$75.60$72.40$67.10Variable selling cost per unit$3.50$4.00$3.70$4.40Monthly demand in units3,9002,9002,9004,900

The grinding machines are potentially the constraint in the production facility. A total of 10,500 minutes are available per month on these machines.

Direct labor is a variable cost in this company.

Which product makes the MOST profitable use of the grinding machines?