During 2021, it cost Sheridan Inc. $12 per unit to produce Part T5. During 2022, the cost has increased to $15 per unit. In 2022, Carla Vista Company has offered to sell the Part T5 for $8 per unit to Sheridan. With regard to the make-or-buy decision, which statement is true? Net relevant costs are $4 per unit. Incremental revenues are $3 per unit. Differential costs are $7 per unit. Incremental costs are $4 per unit. Harrison Company determines that an opportunity cost of an alternate course of action is relevant to a make-or-buy decision. Which statement is true of the opportunity cost? should be added to the "buy" costs should be subtracted from the "make" costs should be added to the "make" costs should be ignored if it does not involve a cash outlay