If the marginal rate of substitution between tea and sugar is constant, then tea and sugar can be considered _____

The U.S. Postal Service

a. has its monopoly status guaranteed by government franchise b. enforces copyrights and patents in the United States. c. owes its monopoly status to network externalities d. is a monopoly because it controls a scarce resource e. has a horizontal average total cost curve

The real rate of interest is the

a. money rate of interest plus the inflationary premium. b. money rate of interest minus the inflationary premium. c. yield one can expect to receive on loanable funds without taking significant risk. d. risk component associated with the ownership of real assets.