Good X and good Y are related goods.Holding everything else constant,if the price of good X decreases and the demand for good Y increases,good X and good Y are probably:

A) complements.
B) substitutes.
C) inferior.
D) normal.

Complements

Goods or services that are used together, where the increase in consumption of one leads to an increase in consumption of the other.

Substitutes

Goods or services that can be used in place of one another; an increase in the price of one leads to an increase in demand for the other.

Related Goods

Products or services that are connected by consumer preferences or demand, such as substitutes and complements.