Question 6 Which of the following is an example of an opportunity cost? a. Apple's investment in the iTunes music store boosted sales of its iPod. b. A firm has land that can be used in building a new store. If the new store is not built, the firm could sell the land for $2 million. c. The cost of a report done 2years ago to investigate the potential of a new plant and the permits required to build it. d. A publisher introduces a new textbook which reduces sales of one of their existing textbooks