Product A requires 7.2 minutes of milling, 7 minutes for inspection, and 6 minutes of drilling per unit; product B requires 5.5 minutes of milling, 5 minutes for inspection, and 8 minutes of drilling per unit; product C requires 3.4 minutes of milling, 3 minutes for inspection, and 15 minutes of drilling. The department has 14 hours available during the next period for milling, 15 hours for inspection, and 24 hours for drilling. Product A contributes $2.0 per unit to profit, product B contributes $2.3 per unit, and product C contributes $4.0 per unit. How do you express the milling constraint mathematically? NOTE: Let A,B, and C denote respectively the number of A, B, and C to be produced. a. A + B + C <= 14 b. 7.2 A + 7 B + 6C <= 14 c. A + B + C <= 840 d. 7.2 A + 5.5 B + 3.4 C <= 14 e. 7.2 A + 5.5 B + 3.4 C <= 840