Answer:
(E) I, II, and III
Step-by-step explanation:
I. Remaining in the class incurs an opportunity cost.
II. The entire tuition is irrelevant because it is a sunk cost.
III. The cost of the book is a sunk cost.
An opportunity cost is the cost incurred when we choose to forgo an alternative option.
Sunk costs are costs that once they have been incurred or spent, they cannot be recovered or gotten back.
If Peter chooses to remain in the class, then he gives up his part-time job. The salary he would have made from the part-time job within that period of time is an opportunity cost he will have to forgo.
Also, the tuition fee and the cost of the textbook (which is now an old edition and worthless) have already been spent and cannot be recovered, therefore they are sunk costs.