Which of the following best illustrates the concept of derived demand as explained in the text?
A.
The number of retail stores in a downtown area decreases and demand for retail goods increases.
B.
An increase in the number of new single family homes results from a spurt in the gross national product.
C.
The heat wave results in an increased demand for air conditioners.
D.
Jet engine manufacturers experience increased sales because more tourists are taking international vacations.
Answer: D