Demand Is Best Defined as The

Demand is best defined as the:

A) amount of a commodity that buyers would be willing and able to purchase at a specific price.
B) price that buyers would be willing and able to pay for a specific quantity of a good.
C) relationship between the price of a good and the quantity people are able to purchase, all other things unchanged.
D) relationship between the price of a good and the quantity people are willing and able to purchase, all other things unchanged.