Final answer:
Opportunity cost includes not just the price of the movie ticket but also the value of the time and any other activities foregone by attending the movie. In Selena's scenario, her $8 ticket is a sunk cost, and if the movie is not enjoyable, her remaining time spent in the theater could be used more valuably.
Step-by-step explanation:
When contemplating the opportunity cost of going to a movie the night before an exam, it is essential to consider not only the price of the ticket but the entire array of alternatives foregone. Specifically, in Selena's case where she has spent $8 on a movie ticket, her sunk cost is the money spent on the ticket that she will not get back.
However, the concept of opportunity cost extends far beyond this initial financial outlay. Should she choose to stay despite the movie being unsatisfactory, she would incur additional opportunity costs in terms of time that could be spent elsewhere, potentially on more beneficial activities.
For example, instead of enduring the movie, she could be engaging in activities that hold more value for her like volunteering, visiting a beloved relative, or working to earn money. The opportunity cost of her staying would then be the value of these alternate activities that she gives up by remaining in the theater. As such, the correct answer to the student's question is 'c. the total cash expenditure needed to go to the movie plus the value of your time.