The owner of a millwork shop is considering three alternative locations for a new plant for building embossed-and-clad steel exterior doors for residences. Fixed and variable costs follow. Since the plant ships nationwide, revenue is assumed the same regardless of plant location. Location Costs A B C Fixed $700,000 $1,100,000 $1,000,000 Variable $28 $20 $18 Which of the following is correct? a) A is cheapest from 0 to 30,000 units. C is cheapest after 30,000 units. B can never be preferred. b) A is cheapest from 0 to 30,000 units. C cheapest between 30,000 and 50,000. B is cheapest after 50,000. c) A is cheapest from 0 to 30,000 units. B is cheapest between 30,000 and 50,000. C is cheapest after 50,000 d) A is cheapest from 0 to 30,000 units. B is cheapest after 30,000 units. C can never be preferred