13) Explain what economists mean by rational choice and think of three choice that you've made today that are rational? 14) Explain why opportunity cost in the best for-gone alternative and provide examples of some opportunity cost that you have faced today. 15) Explain what it means to choose at the margin and illustrate with three choices at the margin that you have made today. 16) Explain why choices respond to incentives and think of three incentives to which you have responded today