The demand curve for a good connects points describing how much consumers

a.

actually bought at different prices during a particular period.

b.

actually bought at different prices in different periods.

c.

would have been willing and able to buy at different prices during a particular period.

d.

would have been willing and able to buy at different prices in different periods.

An upward-sloping supply curve shows that

a.

buyers are willing to pay more for a scarce product.

b.

suppliers are willing to increase production of their goods if they can receive higher prices for them.

c.

buyers are unaffected by sellers' costs of production.

d.

the price of a product is not influenced by the price buyers are willing to pay.

e.

at higher prices, an envy effect begins to affect the demand curve.