9 Which of the following costs are always irrelevant in decision making? (A) Avoidable costs (B) Sunk costs Opportunity costs (D) Fixed costs (C) 10 Research has shown that managers perform best when (A) there is no budget to worry about. (B) budgets contain a maximum of slack. there is a moderately difficult but achievable budget. the budget is obviously unachievable, but presents a tremendous challenge