Thompson Industries has the following short-run cost structure per level of production output: Output Units (Q) Total Costs (TC) Fixed Costs (FC) 30000 $ 240000 $12000 50000 $ 360000 $12000 70000 $ 480000 $12000 90000 $ 570000 $12000 Based on the above and assuming a sales price of $10 per unit, what is the marginal cost per unit if the Company’s output is increased from 50000 units to 70000 units（）

A. $6.86

B. $6.00

C. $4.60