Sage Company is operating at 90% of capacity and is currently purchasing a part used in its manufacturing operations for $17.00 per unit. The unit cost for the business to make the part is $22.00, including fixed costs, and $11.00, not including fixed costs. If 39,773 units of the part are normally purchased during the year but could be manufactured using unused capacity, the amount of differential cost increase or decrease from making the part rather than purchasing it would be a Oa. $238,638 cost decrease Ob. $198,865 cost increase Oc. $676,141 cost decrease Od. $238,638 cost increase Bluegill Company sells 14,300 units at $220 per unit. Fixed costs are $157,300, and operating income is $786,500. Determine the following: a. Variable cost per unit b. Unit contribution margin $1 per unit c. Contribution margin ratio %