Explain what happens to contributions to GDP in each of the following situations.
a. A woman who makes a living charging for investment advice on her Internet Web site marries one of her clients, to whom she now provides advice at no charge.
b. A tennis player wins two top professional tournaments as an unpaid amateur, meaning the tournament sponsor does not have to pay out his share of prize money.
c. A company that had been selling used firearms illegally finally gets around to obtaining an operating license and performing background checks as specified by law prior to each gun sale.