David and Asher buy the same pair of sneakers, but each in the wrong size. David proposes a size swap with Asher. This is an example of a. barter, since the sneakers in the correct size represent a medium of exchange. b. barter, since the sneakers in the correct size have intrinsic value to both David and Asher. c. money, since the sneakers in the correct size do not have any intrinsic value. d. money, since the sneakers in the correct size represent a medium of exchange