Which scenario best exemplifies the concept of opportunity cost?

Which scenario best exemplifies the concept of opportunity cost?

A) Aileen has been offered a promotion to department manager. The promotion means more hours at work and more responsibilities, but includes only a title change and not an increase in salary.

B) Rick has a small bakery that generates a modest profit for him. He knows if he pools his profits for two years he will have enough money to expand his bakery and increase his profits.

C) Keisha has been offered a chance to invest in a startup company that has the potential to generate a great deal of profit if it is successful. Since the cost to invest is very high, she must decide if the potential profit is worth the risk.

D) Esme has enough money to either buy her son a new pair of jeans before winter or get him vaccinated against the flu. She knows that once she chooses one alternative, she will be unable to afford the other.