17. Opportunity costs A. Result in a cash outlay B. Unless they are zero are always relevant for decision making. C. Can sometimes be deductible for U.S. federal income tax purposes. D. Are recorded in the accounting records E. Are the result of a completed event or transaction. 18. In a "make-or-buy" decision: A. Only variable costs are relevant. B. Fixed costs that can be avoided in the future are relevant. C. Fixed costs that will continue regardless of the decision are relevant. D. Only opportunity costs are relevant. E. Opportunity costs are generally zero