A lawyer can argue a case in court for one hour and make $$300.$ She could alternatively use that hour of time to type a legal brief in her office. What is the opportunity cost of her typing the legal brief?

nothing, since she would never type a legal brief

There is not enough information in this problem to be able to answer the question.

$$300,$ since that is the amount she could have made by arguing a case in court

nothing, since she would always hire an administrative assistant to type for her