The correct answer is:
b. has no intrinsic value. The exchange is not an example of barter.
U.S. currency is considered fiat money, meaning it does not have intrinsic value (it's not backed by a physical commodity) but is accepted as money because the government maintains it and people have faith in its value. The exchange for a meal is not barter because money (currency) is being used as a medium of exchange rather than directly trading goods or services for other goods or services.