A restaurateur is considering expanding his restaurant into a chain. They spend $10,000 on market research, and using that research determined that opening a new location in a specific area isn't likely to be profitable. Yet it is really hard to say "Stop!" It's much easier to say "Well, it will be ok if we tweak X" and keep trying than to say, "Yes, all the work we have put into this project and we've wasted our time and money." This line of reasoning is called _______. a. concept testing b. design and development c. the sunk cost fallacy d. focus group research