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 the business to make the part is $20.00, including fixed costs, and $9.00, not including fixed costs. If 31,051 units of the part are normally purchased d the year but could be manufactured using unused capacity, the amount of differential cost increase or decrease from making the part rather than purchas it would be a Oa. $248,408 cost increase Ob. $527,867 cost decrease Oc. $248,408 cost decrease Od. $93,153 cost increase