Goods X and Y Are Perfect Complements

Multiple Choice

Goods X and Y are perfect complements.If the price of good Y falls,what will the substitution effect acting by itself do

A) It will cause consumers to buy more of good Y and less of good X.
B) It will cause consumers to buy more of good X and less of good Y.
C) It will not affect the amount of goods X and Y that consumers buy.
D) It will affect the amount of goods X and Y that consumers buy, but in an unpredictable way.