a) How would you define "public goods"? How are they different from "private goods"? b) Why is it that only the government can be the provider of public goods? c) Please explain the functions of money (there are four of them). Do you think digital money that many of us now use can carry all those four functions? Explain your answer. d) One factor that can influence your decision whether to save or to invest is interest rate. Please explain your answer and give an example.