Answer:
B. Watching TV
Explanation:
Opportunity cost is a term used used to express cost in terms of forgone alternatives. It is a sacrifice made in order to choose something else.
Opportunity cost also refers to the gain, enjoyment, benefits that one would have gain but looses such as a result of preferring one alternative to another. With regards to the above, the opportunity cost of reading is watching TV because one must sacrifice watching TV for a book, hence reading a book means that there will be no TV to watch.
