Challenger Industries produces a part used in the manufacture of one of its products. The unit product cost is $26, computed as follows: An outside supplier has offered to provide the annual requirement of 5,000 of the parts for only $21 each. The company estimates that 75% of the foxed manufacturing overhead cost above could be eliminated if the parts are purchased from the outside supplier. Assume that direct labor is an avoidable cost in this decision. Based on these data, the per-unit dollar advantage or disadvantage of purchasing from the outside supplier would be: $1 disadvantage $3 advantage $5 advantage $4 disadvantage