The correct answer is: C. Substitute.
A PCC shows the relationship between the quantity demanded of one good and the price of another good, holding all other factors constant. The negative slope of the PCC indicates that goods X and Y are substitutes. This means that if the price of good X increases, consumers will demand less of good X and more of good Y.
Goods are considered substitutes if they can be used in place of each other. For example, coffee and tea are substitutes because they can both be used to consume caffeine. If the price of coffee increases, consumers will demand less coffee and more tea.
Goods are considered complements if they are used together. For example, cars and gasoline are complements because they are used together to drive a car. If the price of gasoline increases, consumers will demand less gasoline and therefore fewer cars.
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