The price of good A goes up. As a result, the demand for good B shifts to the left. From this we can infer that:
A) good A is used to produce good B.
B) good B is used to produce good A.
C) goods A and B are substitutes.
D) goods A and B are complements.
E) none of the above

Question

Quizplus · Accepted Answer

The fact that the demand for good B shifts to the left (decreases) in response to the increase in the price of good A indicates that goods A and B are complements. This means that they are often used together, and an increase in the price of one leads to a decrease in demand for the other.

The Price of Good a Goes Up