【单选题】The difference between a change in quantity demanded and a change in demand is that a change in:
A.
quantity demanded is caused by a change in a good's own current price, while a change in demand is caused by a change in some other variable, such as income, tastes, or expectations.
B.
demand is caused by a change in a good's own current price, while a change in quantity demanded is caused by a change in some other variable, such as income, tastes, or expectations.
C.
quantity demanded is a change in the amount people actually buy, while a change in demand is a change in the amount they want to buy.
D.
A change in demand and a change in quantity demanded are the same thing.