Yvette is waiting in line to receive a free t-shirt at a charity event. Because the shirts are free, there are many people in line, and a long wait time is expected Consider the following sentence: By waiting in line for the shirt Yvette will miss an appointment to tutor an economics student, for which she would have been paid $30. Which basic concept of individual choice does this sentence best illustrate? a. Externalities are a shortcoming of the market,
b. Many decisions are made on the margin.
c. Opportunity costs and money costs (price) are related but are not always exactly the same
d. People usually exploit opportunities to make themselves better off.