Answer: Substitute
Step-by-step explanation:
Substitute goods are the goods that can be used for the same purpose. Complement are the goods that are used together e.g. car and petrol.
It should be noted that when the price of a good increase, people move to the substitute and this will being about the rise in the quantity demanded of the other good.
Therefore, as the price of good X rises from $10 to $12, the quantity demanded of good Y rises from 100 units to 114 units shows that the are substitutes.