A company makes four products that have the following characteristics: Product A sells for $75 but needs $20 of materials and $20 of labor to produce; Product B sells for $90 but needs $45 of materials and $20 of labor to produce; Product C sells for $110 but needs $50 of materials and $30 of labor to produce; Product D sells for $135 but needs $75 of materials and $40 of labor to produce. The processing requirements, in minutes, for each product on each of the four machines are below. Product A requires 8 on machine W, 12 on machine X, 8 on machine Y and 10 on machine Z. Product B requires 4 on machine W, 9 on machine X, 12 on machine Y and 9 on machine Z. Product C requires 12 on machine W, 10 on machine X, 14 on machine Y and 5 on machine Z. Lastly, Product D requires 10 on machine W, 6 on machine X, 5 on machine Y and 5 on machine Z. Work centers W, X, Y, and Z are available for 40 hours per week and have no setup time when switching between products. Market demand is 50 As, 60 Bs, 70 Cs, and 80 Ds per week. In the questions that follow, the variable costing method refers to maximizing the contribution margin per unit for each product, and the bottleneck method refers to maximizing the throughput contribution margin per minute at the bottleneck for each product. Other than the non-negative constraints, how many constraints do I have? Answer Options: 8 6 12 10 4