Kristie Currently Spends Her $1,000 a Week Income on X,Y,and

Multiple Choice

Kristie currently spends her $1,000 a week income on X,Y,and Z. Her mother gives her an extra $400 and tells her to use it to buy more Z. Kristie actually takes the $400 her mother gave to her,adds it $40 of the $300 she usually spends on Z,and buys $660 worth of Z. Did Kristie's mother's $400 go to buy only Z?

A) Yes, because Kristie used her mother's actual $400 (four $100 bills) to buy Z.
B) No, because if it had, Kristie would have bought $700 worth of Z. Some of Kristie's mother's money went for what Kristie had next on her list to buy.
C) Yes, since Kristie bought $640 worth of Z, and the amount of money her mother gave her is less than $640.
D) There is not enough information to answer the question.