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In make-or-buy decisions for a part for a product, relevant costs include - A. some variable costs of making the part. B. all variable costs of making the part. C. all variable costs of making the part and fixed costs that can be avoided in the future if the part is purchased. D. fixed costs that can be avoided in the future, if the part is purchased. Nestle Company paid $130,000 for a machine used to mill oats. The annual contribution margin from oat sales is $60,000. The machine could be sold for $80,000. The opportunity cost of producing the oats is . A. $20,000 B. $130,000 C. $60,000 D. $80,000