The circular-flow model shows that _____
a. households are on the demand side of the resource market.
b. firms are on the demand side of both the product and resource markets.
c. governments are on the demand side of the product market and the supply side of the resource market.
d. households are on the supply side of the resource market and the demand side of the product market.
e. firms and governments are on the supply side of the loanable funds market.