During 2015, it cost Westa, Inc. $12 per unit to produce Part T5. During 2016, it has increased to $14 per unit. In 2016, Southside Company has offered to provide Part T5 for $9 per unit to Westa. As it pertains to the make or buy decision, which statement is true? Differential costs are $5 per unit. Incremental costs are $3 per unit. Net relevant costs are $3 per unit. Incremental revenues are $2 per unit.