Final answer:
The opportunity cost of attending the concert instead of going to the beach is the beach experience.
Step-by-step explanation:
The opportunity cost of attending the concert instead of going to the beach is the beach experience. Opportunity cost refers to the value of the most desirable alternative that is given up when making a decision. In this case, by choosing to attend the concert, you are giving up the experience of going to the beach. While options like entertainment, time, and money are all relevant, the most accurate answer is the beach experience.