*ECONOMICS*
What is the opportunity cost in the following scenario?
To finish furnishing her new apartment, Carlisha needed a couch, a table, and a new stereo system to replace her old stereo system. The couch she wanted cost $350, the table cost $100, and the new stereo system was $200. She had $500 to spend. She decided to buy the couch and the table, and keep her old stereo system.
A. couch B. table C. new stereo system D. old stereo system