单选题

The diagram illustrates a consumer's allocation of her budget between items X and Y. With an initial budget (BC₁ ) she consumes Q_a units of item Y. When the price of Y drops, she consumes Q_c un its of item Y. Lines BC₂ and BC₃ are parallel to one another.

A、
Q_b and Q_a .
B、
Q_c and Q_b .
C、
Q_c and Q_a .

【正确答案】 B

【答案解析】

B is correct. When the price of Y falls, the budset constraint shifts outward from BC₁ to BC₂ , indicating an increase in the consumption of Y. Points a and b reflect the change in consumption of Y due solely to a decrease in price because BC3 reduces her income by a sufficient amount to return herto her original indifference curve. Q_c -Q_b is the income effect (which is nesative here) because this is an inferior good.